I think it totally unacceptable for restaurants to add extra charges onto the bill and put the onus on the customer to have these charges removed.
To me, this is no different than if I went to Lidl or Waterstones and had my shopping totalled up as 20.99 and then the shop added an extra 2.09 automatically and forced me to apply to them to remove it; or if the item price said 12.99, but the till was deliberately set up to charge me 15.99.
I see this more and more. I think this should be made illegal under consumer protection.
YABU - it's fine for any industry to add on whatever extra charge they want as long as they eventually remove it for customers who raise it with them
YANBU - customers should only be charged according to listed price for the item/service chosen