It's reasonable that satellites should mitigate the impact on astronomy as much as possible. But it's not reasonable that we should seriously constrain the use of satellites because some astronomers using land-based optical telescopes are inconvenienced.

How would painting a satellite black 'seriously constrain' them? Why do we let corporations foist externalities on science and the general public? Either you can engineer a solution, or you can't, and if you can't, you don't belong in space.

Painting a satellite black wouldn't solve the problem that they would still block the stars behind them when passing overhead. Instead of light streaks, you now have dark streaks across a region of the sky.

These "dark streaks" would be way less of an issue. The reason you get light streaks is that exposure is really long and the satellites move quickly. The fraction of time a satellite is covering any given portion of the picture is really small. If you use, say, a 30 minute exposure, these "dark streaks" will be parts of the picture which only got, say, 29 minutes and 55 seconds. That's not a big deal.

The problem with painted satellites is instead that they're not black enough; they still produce light streaks since they're still somewhat reflective. I don't know if it's possible to make them non-reflective enough to make this a non-issue.

I mean that's like saying that a star's brightness isn't a problem when searching for exo planets, and they only block you from seeing the objects behind them. Obviously that's not true. Light pollution from orbital satellites is a real thing.

I don't design satellites so I don't know. As I wrote, if there are reasonable measures that can be taken to reduce the effect of satellites on astronomers (or potentially creating space debris) they should be taken. However, there's a clear trend towards more (cheaper) satellites that serve useful purposes. And I very much doubt the public cares much about any inconveniences it presents to academics in this case.