These types of hinge and spring system for one piece garage doors are very old and are usually pretty rare to come across but they are still out there & I have seen a handful in my time as a garage door technician and if your main question is are they dangerous just because of the way it looks your answer is absolutely yes that spring could break and it will send it flying into the back wall of the garage now if a smart technician had caught the danger they will have installed a safety cable this cable runs through the middle of the spring is tied off to the front of the spring and the rear of the spring where it attaches to the wall this safety cable will keep the broken pieces of spring from flying in random directions causing a lot more damage than if the spring has a safety cable installed. What this safety cable does is allows the broken pieces of the spring to slide along the cable contained somewhat. An experience I had with a customer that had a door like this and she wanted to turn the garage into a playroom for her kids and I told her that would probably not be a good idea unless she converted to a sectional roll up garage door because I would not have any of my children playing in that garage with that volatile of a problem. Most of the springs can be of industrial size and strength and are usually made to last a really long time but without a safety cable I just wouldn’t trust it. Would not surprise me for a spring like that to break and hit someone and cause serious injury or death.
the old wood garage door
If you cannot convert your garage door right away and need more time then you should at least have a garage door company come out and install a safety cable in that spring just to be safe until you can convert your garage into a sectional roll up style garage door. Or if you actually like the design of the old wood garage door that you have because it goes with the style or architecture of your home then you could convert the old style spring and hinge system with a more modern hinge and spring system for better safety and functionality. This is also something that a good home inspector would catch when he is inspecting your home to a garage door technician it sticks out like a sore thumb but it may not to some home inspectors so this is something you might want to keep in mind if you see this kind of hinge and spring system when you are shopping for a new home. Anytime you have a one piece garage door in a home that you are thinking about buying you should ask anybody who is going to inspect the home for you to really look at the garage door to make sure it is going to be safe and if they would recommend that you convert to a sectional roll up if needed. I find these types of garage doors in certain regions of the United States especially the colder regions where you get a good amount of snowfall in the winter it seems that these garage doors do not work well in these regions because of the way that they open. Your garage door can pretty much be stuck closed if you have a couple of feet of snow on the ground so you will usually find these types of garage doors towards the western part of the United States and the West Coast.