Its so easy for humans to die from a random accident, but very hard to deliberately end their own lives reliably and painlessly.

These seem like arbitrary rules. Most random accidents don't reliably kill people and are also painful. You're comparing a tiny subset of random accidents to all intentional suicide methods as if they are or should be somehow similar.

On the other hand, people pull off some of the crazies stunts and accidents without getting killed.
Let's say you're flying on plane that has bomb onboard. The explosion shreds the plane to a million pieces in mid-air and everyone dies... right? Not necessarily.

Username checks out.

Fun fact: That's the Christian belief of the Cathars. They believed God was allowing evil, and the mortal realm is the domain of satan entirely, and we're here specifically to suffer.
Then modern day "christians" killed them off because they've actually always been vile controlling pieces of shit.
- Is there any connection to the word Catharsis?
  
  Yes! They both have the same Greek root, katharos, meaning purified.

This is not very well thought out. People survive accidents all the time, far more than they die from them. It is confirmation bias that makes you feel like it is easy to die from one because people only focus on the bad ones. Normal injuries and close calls fly under the radar.

It is NOT difficult to kill yourself intentionally, at all.
Make a simple, strong slip knot to use as a noose, secure it somewhere that will support your body weight, tie your hands behind your back so that you can't easily get out of the restraints, and jump off a ledge of some kind. It won't break your neck and you'll die agonizingly, but you will almost certainly die of asphyxiation. Even more effective if you tie yourself up in weights and jump into deep water.
Shotgun. Easily procurable in America. Stick in mouth with buckshot and pull trigger. Messy, but effective.
Lots of ways to make powerful bombs with materials you can find in stores. Make one and set it off in your mouth.
Lock yourself in a room with carbon monoxide. So long as no one's coming to get you, it's a nice, peaceful way to go out.
Snort a sugar cube's worth of fentanyl.
Sever any major artery and get in a bathtub full of water so the wound can't seal easily. Cope with the pain until you pass out. As long as no one finds you, you dead.
I could go on, but I think I've been morbid enough.
Thankfully, suicidal impulses are just that: impulses. They are relatively short-lived (10-20 minutes on average) and then they pass. You may still be depressed, but the urge to end it all is no longer there, for most people. One of the best things you can do when you're feeling suicidal is just to go to sleep. When you wake up, you'll likely feel better. The vast majority of people who attempt suicide and live regret it almost immediately, and most of them do not attempt it again.
However, there are people who enter long suicidal states, where they've genuinely made up their mind to end their lives. With these people, no matter what the psychiatric intervention is, short of permanently restraining them, they will almost always find a way to kill themselves. The truth is you cannot stop a person who is truly intent on ending their life. And I for one am very thankful for that, because living should always be a choice. We should not be in the business of forcing people to live torturous, agonizing lives from which there is no real escape or remedy. Everyone should have the option of "getting off the ride" if they so choose. Ultimately, it's no one's business but their own.
- Those are all going to traumatize whoever finds you, and are otherwise uncomfortable ways to go.
  Dignitas uses nitrous in their pods. Pretty chill way to drift off forever, so long as you ensure a means to get rid of the CO2 to prevent that ‘suffocating’ feeling.
  
  Yeah, my point was simply that it’s not hard to kill yourself, like the OP asserted. Obviously, many people would have other considerations in mind (e.g. pain, the state of your body afterwards, etc).
- The gun and the bomb are difficult to mess up, but people survive those
  
  I don’t see how you could survive a shotgun blast to the back or top of your mouth, much less a bomb. At the very least, the brain stem is vaporized, and you can’t survive without that. I suppose if you turned the barrel to the side and just blew out your cheek and jaw, perhaps, but that’s being stupid.
- Other than the fent and bomb one I have heard stories of people surviving. Heard a load of people surviving making explosives that went wrong so. Feel sugar cube fent is the only truly reliable one.

There's hope, though. Although stalled by the current civil liberties regression phase we're going through in the States, and the rise of fascism globally, in some States and some countries assisted suicide is legal. There's a wonderful product called the Sarco Pod, developed by an Australian, that performs euthanasia by nitrogen, which is one of the best methods of suicide. It's not currently widely available, but hopefully services offering it will start popping up. We have to get through this rough patch, first.

100mA and 100v with good conductivity. More Amps more certain. More volts, less need to lube the conductivity.
1kV and 1A, dead as fuck. Basically 0 chance of survival if it crosses your chest.
10kV and 10A. Literally incinerated.
Electric chair was about 2kV and like 7.5A
Electricity doesn't leave destruction to chance.
- I got constantly zapped by static electricity in the winter like every year and that was painful, I think death by electricution is extremely painful, no thanks.
  
  I don't think you'd feel 10kV and 10A. But less, you might and it'd probably be horrible.

There are no guarantees in life, or death.

Humans are quite resilient though.
It is just that we have weaknesses like illnesses that can take us down in a moments notice.

It's not really that hard though.

- Symptoms of [nitrite] poisoning can vary depending on the amount and duration of the exposure. Those with very mild methemoglobinemia might not have any symptoms at all, or might appear a little pale and feel tired. Moderate-to-severe poisoning is associated with cyanosis (blueness of the skin), confusion, loss of consciousness, seizures, abnormal heart rhythms, and death.
  It's it supposed to be special in some way?
- Death by bacon?