Why do people hate Scousers?

But the Manc/Scouse divide was apparently born of the time when Manchester's cotton workers refused to spin cotton farmed by slaves (and recieved a letter of solidarity from Abe Lincoln) whereas the scouse dockers kept on accepting the shipments.

There we go, so a Manc accuses Scousers of living off the wages of slavery/racism. In fact Liverpool has always had a great tolerance of people from other places and has been ethnically diverse well before the rest of England. (one of the first chinese / Oldest jewish / and Caribbean communities are in liverpool)

According to wikipedia the rivalry is because the Mancs didn't want to pay port tariffs to Liverpool port:

The rivalry is generally agreed to have ignited after the construction of the Manchester Ship Canal. Manchester merchants became disenchanted with the level of dues they had to pay to exports their goods. Consequently the Mancunian merchants decided to construct a ship canal. The Ship Canal would become the largest in the world upon opening in January 1894 and highlighted the length the merchants were prepared to take to avoid paying dues.[2]