What exactly is taking all these states so long?

They are making sure to do it right.

They started counting the mail in votes later than other states. In PA, mail in votes weren’t counted until 7 am Election Day. I forgot which state it was but it couldn’t start counting mail votes until after the election. 

PA has way too much votes and not enough people to count.  It has over 7 million votes. There’s going to be as high as 88,000 overseas votes tomorrow so they need to get counted. 

The race is too tight to call so every vote must be counted before a winner is declared. Look at GA. 4000 votes separating them. There’s still maybe tens of thousands of votes that needs to be counted because theoretically trump can still win. 

They have to count and recount, then verify and reverify, then they have to recalibrate every voting machine every ten votes to be sure they are counting accurately. If Don needs 100 votes to win, and there are five ballots left to count, they still have to count them or the trumpanzees will have a screaming fit.

Probably because Trump is trying to legally suppress their vote counting process.  

Ballots mailed on the election day has not necessarily arrived yet.