These are typical errors made by the native speakers. Most (every?) language has rules, which are more difficult for a native speaker to follow vs. a well-spoken foreigner.
Other examples in English are:
- who vs whom
- then vs than
- ask vs acks
Other examples in English are:
- who vs whom
- then vs than
- ask vs acks
I prefer to call both of them mistakes. :-)
Otherwise we just end up accepting anything as valid, anything as a proper usage. The spelling bee loses any sense, because all the losers will claim that they were simply speaking/writing English in their own way.