I’m close to you in age and don’t ever recall local DL hotels offering transportation to Knott’s. There was a shuttle to Universal that stopped at multiple hotels, but it was not offered by the hotels themselves. Nor was it free but may have included with admission at one time (not latter years).
20 years ago nearly every hotel had a shuttle to DL but only a few remain. I guess that’s what Anaheim kinda wanted with the ART although the busses are ridiculously deserted (maybe sans opening and closing) these days. Probably why they’re moving to an on demand system.
Most of the Anaheim area has been cleaned up and gentrified in the last two decades and walking is a pleasant option. I even walked to the DoubleTree Orange not long ago - they’ve really cleaned Manchester up, although it gets seedy for a bit.