Does Google ask the restaurants for permission to do that? Couldn't they get sued for damage of reputation when they show wrong prices?
On a slight tangent: bear in mind also that Google is not party to whatever agreement there is between venue and customer, which is why it's so foolish that one frequently sees people asking questions on Google Maps as if they are directly communicating with the venue. Eg people ask "Can i get a child's cot in my room" - all it takes is for some joker to say yes, the naive asker to proceed to the venue and then find out that they offer no cots, at which point naive person has no leg to stand on (venue quite rightly says we've no idea what you're talking about).
Do they? The article says there's "no way for a user to contact Google".
However, putting that aside: Venues/business owners can contact Google and i suspect would get a slightly better response rate (not saying it'll be perfect or even super easy for an owner to get through but they can as there are often links indicating "Are you the owner of this business?")
I can't imagine this creating much of a barrier - Google would stop if told to by the restaurant but then they might not list the restaurant, and what restaurant would see that as worth it?