WFH doesn't actually stop driving. They don't commute, but they do run errands and other stuff during the day. This can actually result in more traffic during high peak periods since it can cause congestion build up to start earlier

but then again, vehicle miles travelled per-capita has been mostly increasing in the US since as far back as 1975. There could be a lot of confounding factors. Like astronomical housing prices in urban areas forcing people live very far away and incur more VMT at a faster rate than WFH decreases VMT. I'm no expert here, I'm just spitballing.

Because people didn't go back to taking transit

I think the bigger point was that pandemic traffic immediately showed effects. Smog cleared up in Los Angeles in less than a month.

But no, it won't ever be that level without major infrastructure change. Not all jobs can be wfh. We can get close by a major public transportation overhaul, but that will take decades (even without the inevitable pushback).