It's even worse than implicit casting, if the value can't be cast to the the column's type, it's just inserted without casting. Eg. into an integer column, '10' -> 10 and '1O' -> '1O'

That is documented behaviour - think of it as making a best effort, and not losing the value.

As of January 2006 you could add CHECK constraints using the TYPEOF function to reject that at the SQL level. And it is your own code - there is no server - doing the insertions. As was common back then, protecting you from your own bugs was not a high priority for APIs!