That's a terrible example. In the US that's exactly how restaurants work.
In Europe if the meal deal says 20 euro it costs 20 euro (inc. taxes and tips are legitimately optional). In the US if it says $20 it costs $20 + 5% hidden tax + mandatory tip (15-20%). So in the US a $20 meal costs $24.15 (15% tip which I'm told is the minimum).
That's the way the entire US society is set up top to bottom. Hidden fees, surcharges, and required "tips" on every single thing. You cannot even use an ATM without being hit for a $3 fee now.
Yet whenever anyone brings this up everyone flocks to defend the practice, like people who want an inclusive price are bonkers! Sorry but American pricing is screwed up, stuff like this is the normal rather than the exception unfortunately.
Consumer laws actually make that kind of charging completely illegal in the EU. Price transparency and all that jazz.