Even in most universal healthcare countries dentistry and vision are only covered for minors, because they’re seen as care that can be budgeted ahead of time (you know a tooth is sensitive waayy before you actually have it filled, so you can save up for the cost). Dentists and opticians are run like businesses.

And yes, $200 is still ridiculously expensive for a filling. Here in The Netherlands I’d pay ~$104 for a multi-sided composite filling (the most complicated filling you can get). For the cheapest (one-sided amalgam) I’d pay ~$25. Local anesthesia would be ~$8.