That’s also very common in the UK, and shows up elsewhere in Europe sometimes. In the UK, they are legally but not practically or socially discretionary. There are some tax advantages for the restaurant and in the ideal case for staff.
Touristy places in central London maybe. They wouldn't dare try sneaking an undeclared service charge onto a locals bill in Northern England or Scotland :-)
> In the UK, they are legally but not practically or socially discretionary.
Speak for yourself. When entertaining clients at touristy places in London, one routinely asks for this underhand charge to be removed from the bill. (Whether or not we then choose to leave a cash tip is a matter of discretion, but the chances are rather low after such shenanigans).
Adding an undeclared "service charge" to the bill only when it is presented to you is what we are talking about here. It is an increasingly common underhand tactic in and around London and an charge which one should ALWAYS ask to be removed ("that wasn't on the menu mate").