"Read" maybe too strong a word, but I at least take a glance around thsoe documents, and have always done, for almost two decades now.
It's similar to reading code in a boilerplate-heavy language. It's hard at first, but once you've read a few, your brain learns to filter out the chaff and get to the juicy bits. I'm not a legal expert at all and I don't expect to detect intentionally tricky language or other such traps, but even a 20% understanding of these can get you 80% of the value, in learning how broad the rights they give themselves are, how much they're willing to commit to restrictions on themselves (regarding your data, etc.), and maybe learn a thing or two about how the legal system works, too.
