I can, I’ve written a billing system before (unfortunately). There’s a lot of annoying math/edge cases and systems to sync between.

While I never implemented a restriction like this, it would have prevented a lot of weird bugs/customer support issues and kept the underlying code much simpler.

(Annoying math = time zones, prorations, discounts, billing cycle anchors, etc. see the “falsehoods programmers believe about X” series)

(Systems to sync between = internal DBs, billing APIs, payment processors, etc.)

I mean sure, I get it, but companies like Uber leave edge cases like that out when it hurts them (customers cancelling) but move heaven & earth to remove them when it helps them (I bet its easy to re-join within 24 hours of cancelling?).