That makes pretty bad business sense, and given that the bus industry is (largely) private sector is unlikely to happen.
You wouldn't put a tri-axle double decker on every route, probably wouldn't fit through little villages. Neither would you put a minibus on every route, it often wouldn't cope with passenger numbers. For that same reason a uniform service wouldn't work.
You could probably get away with charging a bit more and putting wifi/charger equipped buses on a university route with a clientèle that would appreciate it, but put that on a route through an area popular with 'older professionals' and pensioners and it would be wasted. Again you could charge more for a nicer bus (Citaro with high backed leather seats maybe?) when travelling through a 'well to do' area of a city, but a cheap and cheerful old Excel chugging along until it's next breakdown would suit an area of deprivation and low employment.
Like any product, it works best when targeted at the consumers. Although I share the view that buses can and probably will move upmarket, we as an industry need to appreciate that it's not as black and white as it used to be. There are a number of different markets and each need different products and delivery strategies.
Further reading: everything about Trent Barton