If you’re directly interacting with any sort of binary protocol, i.e. file formats, network protocols etc., you definitely want your variable types to be unambiguous. For future-proofing, yes, but also because because I don’t want to go confirm whether I remember correctly that long is the same size as int.
There’s also clarity of meaning; unsigned long long is a noisy monstrosity, uint64_t conveys what it is much more cleanly. char is great if it’s representing text characters, but if you have a byte array of binary data, using a type alias helps convey that.
And then there are type aliases that are useful because they have different sizes on different platforms like size_t.
I’d say that generally speaking, if it’s not an int or a char, that probably means the exact size of the type is important, in which case it makes sense to convey that using a type alias. It conveys your intentions more clearly and tersely (in a good way), it makes your code more robust when compiled for different platforms, and it’s not actually more work; that extra you may need to add pays for itself pretty quickly.
You mean the places that did the actual research and development on how to effectively build (high speed) trains and rail networks took longer to get where they are than the place that could just use already well-established technology? No way!
Don’t get me wrong, there can absolutely be political barriers to having a good rail network (as evidenced by the US), but let’s not pretend you’re comparing apples to apples here.