Current final year dental student pitching in here. While dentists of the past may push for unnecessary annual radiographs, the curriculum in dental school has changed to favour evidence-based dentistry. Annual bitewings are only indicated if you're a high caries risk, and, as the article mentions, 2-3 years if you're low caries risk. So your younger/newer dentist will be following much better protocols (and hopefully not scamming you)!
How about for cavities? I remember reading an article recently about major increases in the number of cavity related treatments because $$$. My kid has had multiple recommendations for cavities and I've got some suspicions about the absolute necessity of all of it.
Fillings are definitely a staple of the procedures a dentist would perform. The article does mention overtreatment, so really depends on your child's caries risk. As mentioned in another comment, healthy dose of skepticism is always required. I usually try to show signs of decay either intraorally or detected on radiographs.