Bikes are very simple. If you can work on vintage cars and motorcycles, you can work on bicycles.
Parts are easy to find. Bike shops, Department Stores, E-Bay, Amazon, various online bike specialty shops, etc.
Then thing is that quite a few parts have been optimized for bicycles. Perhaps using a slightly different language (as you found with bike tires).
And, just like in the car world, there has been a little over a century of evolution of bicycles
So, while 1/2 x 1/8" chain may be standard in the industrial world, the use of multi speed rear clusters, and a demand for more and more sprockets has led to the evolution of bike specific chains that have been growing narrower over the years.