> It's strange that the list of buses is sorted by bus number and not by time…

You don't randomly hop on the first bus that arrives at your bus stop. You need the bus that brings you to your desired destination. The bus number is important to know you're on the right bus. Sorting by bus number makes it easier to scan for arrival time of the bus you actually need.

Also, every route can be displayed on the board, even if the next ten buses are all on a different route with better service. Better to have the next bus for every route than just the next expected buses

But there might be different busses which share the same route for a while: so you'd rather find find the first one.