Leftpad isn't complex. It just adds spaces. Datetime libraries are complex because they need to do things like deal with the fact that North Korea switched Tim

Leftpad isn't complex. It just adds spaces. Datetime libraries are complex because they need to do things like deal with the fact that North Korea switched Timezones last year, that Fiji is changing their DST dates this year and other crap. We get about 3 to 10 releases of the TZ database every year and you'll probably want the updates as quickly as possible in your Datetime library to deal with timezoned data correctly, otherwise your Customer from Fiji will find that you aren't turning up for the meeting because you left an hour earlier believing the customer wasn't turning up at all. And then you have to deal with dates in the past where there might be possible changes to the entire calendar! Or different calendars such as the Japenese, Chinese or Jewish years. I don't think it's valid to suggest that leftpad and datetime libraries are even on the same order of magnitude of engineering complexity.