No clock is perfect. Computer clocks and data types assume exactly the same amount of seconds per day. Adding leap seconds to clock code makes it unnecessarily

No clock is perfect. Computer clocks and data types assume exactly the same amount of seconds per day. Adding leap seconds to clock code makes it unnecessarily complicated. Leap days have a well behaving algorithm, but leap seconds require a lookup to a table that changes over time. Also maybe people look at the raw data for dates. If we stored a different format, inevitably people would store both forms, and every time you programmed you would have to ask which form is it in. TAI is for things like GPS and missiles where super accurate timekeeping is crucial. Most computers are crap at keeping time and quickly drift. They make calls to central time servers that are better at time keeping, that is where the smear occurs. For most computers their normal drift is in the same order of magnitude as the smear, so it’s not noticeable. Also most distributed programs realize time stamps are not always correct, and when temporal ordering is crucial other methods are used.