Why no built-in TBC in 1980+ VCRs?

[ppppenguin]

A very few did have TBCs. Panasonic FS100 and FS200 come to mind. Also the WC-01(?) which could do standards conversion PAL<>NTSC, albeit not very well.

Purely a matter of cost and whether people would pay for it. Since all TVs of that era would lock to uncorrected VCR outputs.

In a pro environment you needed not just timebase correction but also the ability to lock to an external reference.