The origins of English as spoken today really stem from the Norman conquest. The Norman rulers spoke French, all documents, including the bible, were written in Latin. English was only spoken by the common folk who had been enslaved by the French (and yes, I expect the French to take the knee and apologise to my ancestors
).
Hence English was an everyday language created and modified by ordinary folk. The result was a very dynamic language subject to continuous modification. So with that in mind, buss may strictly be incorrect but if enough people use it then it will become part of the language. (I suspect tis is true of most languages).
Cheers
Ian