Why the past tense? Google is holding on to all of that, going back years.

Yeah, they have all the raw data (Google is a self-confessed data hoarder, after all), I'm sure they have research projects where they use AI and similar to stitch street view images together.

I also wouldn't be surprised if their Street View cars / people record video instead of stills these days. Assuming they started capturing stuff in 2007 (and it was probably a lot earlier), storage technology has improved at least tenfold in terms of storage (probably more), video processing too.