Why is 12 o'clock noon not 12:00am. 10am, 11am, then 12pm. That doesn't make any sense. The AM should turn into PM only when the numbers reset to 1. Better yet, just use a 24 hour clock and there will never be any confusion at what time you mean.
The alphabet. Why does c exist? It only makes two sounds that are already made by S and K.
Buttons that say Click here to restart now, or will automatically restart in 60 seconds. This used to be on window OS installs. The only option I'm given is actually no option at all. Why not restart immediately since I have no choice in the matter anyway?
Why is eleven and twelve not pronounced firsteen and secondteen? Or oneteen and twoteen?
Companies that advertise letters in their phone numbers, like 800-CALL-NOW. We all have phones on us all the time now we dont need this. It's more difficult to decipher the number, and some cell phones with qwerty keyboards don't even have letters on the number keys anymore.
Lower case i's and and uppercase l's needs more differentiation in many fonts.
Why is "everyday" a word but "everytime" is not?
Why don't we have the date written as Year, Month, Date. Biggest to smallest. Anyone who puts dates in their folders or file names knows the Year Month Date message works the best at keeping your folder in proper order.