Why no built-in TBC in 1980+ VCRs?

[kf4rca]

I have a late model Panasonic VHS that has a built in TBC.
Have you ever heard of an ADDA ESP2? That was a sweet little box. It would do everything!
It was a 2 channel Frame Sync, Still Store, or DVE (digital video effects) depending on what mode you used it. Unfortunately it was an 8 bit box so it was a little noisier than the later 9 and 10 bit boxes. The one at our station lost a channel. Nobody knew anything about it. So, on a hunch, I changed the Z80 microprocessor and that got it back!
Haven't seen any for quite a while. So people who have them are holding on to them.