The show was originally produced in part by Paramount Television, which was later acquired along with CBS by Viacom, and when Viacom split back up into CBS and Paramount, CBS got the television properties.

When Paramount was releasing (https://en.wikipedia.org/wiki/Taxi_(TV_series)#Home_media) the sets (https://www.amazon.com/Taxi-Complete-Judd-Hirsch/dp/B00MWP70SG), everything was intact. When it became a CBS (https://www.dvdtalk.com/reviews/39963/taxi-the-final-season/) show, CBS hacked out every bit of music they could from the episodes because they're cheap as hell. I think the only thing they left in those last two seasons was the Stevie Wonder song.

I think so. Some music was retained but most was cut. Stevie Wonder’s Song was left intact as well as Love Me Tender sung in Latka’s Language, the scene in Elaine and the Monk where they danced to them humming Heaven from Top Hat was also left in.