A few hundred points accelerating at 1g is still plenty of energy. It also comes with it's own challenges when it comes to releasing it.

It also provides a constant force, whereas the force required to raise a garage door linearly decreases the higher it gets. With the consequence that a garage door with a failed motor would slam into its stops over your head rather then into the ground. Followed shortly thereafter by the now liberated counterweight slamming into the ground.

https://www.physics.smu.edu/scalise/www/misc/bricks.html

*Wrong link

Plus a counterweight is a big fat weight hanging in midair, so it's pretty obvious what will happen if you let it fall (and where it will land), whereas with a spring it's much harder to tell whether it's under tension or relaxed, and what it might do when the tension is released...

That'd be feasible for new-build uninsulated steel doors, but 200+ lbs of chain for wood doors is a lot.

you have an odd definition for "easy" I think.

garage door springs are safe if you are careful and you use the correct tools and procedures. the instant you take a shortcut with these, you increase the likelihood of a bad outcome.

so, don't take shortcuts, and don't do the work if you don't know what you're doing.

the professionals know this and that's why we pay them, but they're not special creatures with special abilities; they're people who understand that this is a situation which can bite you, and they act accordingly.

Just about anyone can change their garage door springs, if they do so correctly.

Deep shafts have a tendency to flood. And that’s assuming you can drill one in the first place.