The alternative is counterweights. Not exactly new, but there looks like there is enough space for them in this case. The ones in the house I grew up in were a pair of concrete cylinders on either side of the door, maybe 10-15 cm in radius and 1m in length, mounted vertically. Not sure why they're not more common - seemed a completely reliable system.

The door needs less counter weight as it goes up. In order for weights to work you either need several weights, with different weights bottoming out as the door rises. Or have the cable on a spiral pulley may work.

I don't think that's true of the mechanism I saw, which I believe was quite common, but it's 20 years since I looked at the mechanism.

Ok I've found a video with one in: https://m.youtube.com/shorts/zLuJYlHBSkU

The counter weight is always taking the full weight of the door, there's just a linkage which rotates the door on the way up. So, not the same as the spring ones, which follow a curved channel.

This makes me less keen on them as in theory it's going to fall when it wears out, albeit with only 50% of the weight. Unless there's another failsafe.

Thinking about it, the failsafe should be that if one side fails first, it gets stuck against the track. Although I don't think the one in the vid would, because the track points inward

Some gas piston would be cool.

I don't entirely understand why you can't just have a motor move the door for newer aluminum doors. They aren't that heavy.

Coincidentally I just had a professionally done garage door spring replacement today, and I asked the repairman this question, and here is what he said:

1. The springs lift the door from the bottom, and from each side, which puts less load on the door itself as compared to if the entire weight were being lifted from the top middle every time.

2. The motors can be smaller, quieter and use less power

3. In case of power failure, the door is much more functional and safer the less apparently weight it has.

Also the springs themselves are very unlikely to be dangerous (as long as you don't try to replace them yourself), because he said they almost always break when the door is at the closed state, because that is when they are under the most tension. Therefore on the whole, the springs in practice offer no practical safety risk, while greatly increasing the safety of the door in it's normal operation while also reducing wear and tear on the door. They also allow people to have heavier types of doors if they want them.

Because if someone needs to open the door and the power's out, or the motor has failed, many people won't be able to do it.

That might be acceptable day-to-day, but, if opening the door is what's required to escape, say, a house fire, it's very much not acceptable.

Should be a door or egress window in any garage.

Kind of hard to get a car out the door or window. Usually getting a car out of a garage isn't a big deal, because who actually puts their car in there? But also, you don't need to drive your car out if your structure is on fire ... OTOH, you may want to drive somewhere else if your power is out, especially if it's out for an extended period of time.

They do. My gym has a garage door like this. Because of the lack of springs, I didn't realize it had a door opener until the owner went to lower it.