I think this is key. I'd also want to know what the average (I assume all-inclusive with quick lane etc) was before 2020 before inflation took off. 'Our service bill at the dealer was over $500 today!', for the first time is a much different conversation than 'Our service bill at the dealer today was over $500 AGAIN'.
Everything costs more and I think a lot of people are still adjusting. Trading into a new car will only alleviate those service costs if the new car comes with a maintenance plan, which could be a huge selling point if you're trying to buy out of the service drive. My thought is you need to be having these conversations in service along with plans in place to keep service retention up. Because we all know what happens when a customer feels like the dealer service bill is too high, hello independents!