Bad grammar!

[Le Chat]

I have noticed with the passing of years that quite alot of people now say 'we was' instead of 'we were' and 'I wish I was....' instead of 'I wish I were....'
This is an example of how bad grammar has sneaked into our language and is normal now for some people.
I have just been reading through Trip Advisor and otherwise perfect posts are spoilt with this incorrect use of the verb 'to be.'
The other thing I have noticed is that the perpetrators tend to be from southern parts.
Why has this happened?

[tenrec]

My pet hate is "could of" instead of "Could've".