I'm incredulous that that can be the case anywhere.

I live in a wealthy jurisdiction, and the road markings here largely are not what I'd consider to be "perfectly visible". I'd guess that currently, probably 3/4 of painted lane markings have one or more of the following issues: a) obscured by snow/ice, b) faded c) road under construction and lane markings don't correspond to current lanes.

This just goes to show how even unperceptive humans are better than the most perceptive car logic.

Where the car would freak out and stop, you don't even notice anything is missing.

If you ever visit a city that gets substantial snowfall, road markings are essentially nonexistent, even when the snow and ice melts in the spring.

Assuming you're right in that estimate, the hard work is getting more 9s. As a total kind of spitball number, you want 4 more of them.