The short of it is that just because I control a domain name today, that doesn't mean that I control it tomorrow. I could switch to a different hosting provider (and thus the prior hosting provider shouldn't keep getting certificates for the domain they were hosting on my behalf), or I could sell the domain name to somebody else.
The rules that all publicly-trusted Certificate Authorities have to follow are codified by the CA/Browser Forum, which may be helpful for you to look at if you're trying to understand the core rules. They currently allow for reusing domain authorizations for a longer time (around a year if I remember correctly), but Let's Encrypt currently only allows reuse for 30 days, though they have at least at one point considered shortening it to as little as 7 hours. The general industry trend has been toward shorter certificates and shorter validation times, to minimizes the chances of someone having a certificate that they shouldn't have anymore.
The premise of this question is a little odd to me. "Going through authorization" should be an easy, automated process, that a human wouldn't even notice. And for those few cases where it isn't, then the shorter lifetimes and needing to reauthorize more often can help incentivize those few holdouts to make it automated.