If planets like Earth were very rare in ways that didn't change much with time you'd still see a time that was typical

The time measurement is not the only rank measurement we have. We also can compare the sun vs other stars, and it is mediocre across measurements.

Rarity requires an (intrinsically unlikely, ala solomonoff) mechanism - something unusual that happened at some point in the developmental process, and most such mechanisms would entangle with multiple measurements.

At this point in time we can pretty much rule out all mechanisms operating at the stellar scale, it would have to be something far more local.

Tectonics as rare has been disproven recently. Europa was recently shown to have active tectonics, possibly pluto, and probably mars at least at some point.

For later evolutionary development stuff, it will be awhile before we have any data for rank measurements. But given how every other measurement so far has come up as mediocre . . ..

We can learn alot actually from exploring europa, mars, and other spots that could/should have some evidence for at least simple life. That can help fit at least a simple low complexity model for typical planetary development.