What environment are you in where you have to work with birthdates, you have timezone aware dates, times, and intervals, but you don't have a naive/plain/local date type that already exists forcing you to use strings in place of date-without-timezone?

You seem to have a reasonably expedient solution for that problem, but it is surprising to have the combination of things you have to have and things you have to be missing to have that problem in the first place.

They may have something that's just not as easy to work with as strings. E.g. in Swift, you have DateComponents, but that's too dynamic (and Date is sometimes referred to as naive, but that's a misunderstanding, since they are timestamps, not date+time).

Javascript/swift/kotlin frontend, python backend, mysql server. The problem wasn’t that I had access to zero (presumably) well implemented time abstractions with all the bells and whistles, it was that I had five well implemented native time abstractions.