> In many USA restaurants, the waitstaff tips are also shared into a pool

This doesn't change anything because the incentive is still to drive up the bill to drive up the tips. This is caused by the staff being primarily paid in tips.

> The chain restaurant could just "overstaff" with dedicated table runners with no need for a "full hands" rule.

Unlike servers, bussers and runners are generally paid minimum wage or close. Only over staffing servers helps make more income. Over staffing support staff runs up costs.

USA restaurant staffing is widely studied and your personal anecdotes don't change the conclusion: compared to most anywhere else, restaurants in the USA are over staffed with servers.

>Only over staffing servers helps make more income.

There are several gaps in your assertion about USA restaurants being overstaffed with servers.

#1 the mathematical relationship between servers and income is questionable: Servers acting as quasi commissioned salespeople by upselling patrons on "another beer?" or "anyone here want to order desert?" ... can be time-staggered interactions across multiple customers as the server rotates among their assigned tables.

Let's say, a restaurant has 20 tables and initially has 5 servers. Each server rotates among their assigned 4 tables. For a single turnover of 1 set of 20 tables, the diners have been asked(upsell) "Do you want desert?" 20 times. Let's say the owner wants to "overstaff the # servers" to be 1-for-1 and have 20 servers to 20 tables. The # of upsell events is still the same at 20. In what scenarios do overstaffing servers increase restaurant's income? (On the other hand, understaffing servers causes diners to twiddle their thumbs for half an hour after they finished eating because the overbusy server hasn't gotten them the final bill yet which causes less turnover of the tables which leads to less restaurant income.)

It's also not clear why you need tipped servers to upsell. Fast food places like McDonalds have trained minimum wage workers to constantly upsell... "Do you want fries with that? Do you want to upsize that drink?"

#2 the economics equilibrium of what tipped servers want to be paid and whatever staffing levels the restaurant owners want. Trying to overstaff the restaurant means waitstaff notice they don't work as many tables which means their tips (thus total income) is lower. This causes them to quit, which then causes the restaurant to keep trying to hire new waitstaff. Many restaurants chronically run "shorthanded" because of this negative feedback loop. (Which is one of the causes of extra delays between the hostess seating the diners and the time the waiter finally shows up.) Therefore, adding more servers to increase restaurant income isn't going to work.

>USA restaurant staffing is widely studied

The only studies I found analyzed restaurants not being able to hire staff including the servers. No study talked about restaurants having overstaffed servers in the USA as a proven driver of extra income.

EDIT to reply: >In Europe a typical place with 20 tables will have 2-3 servers and no runners. We go from 8-10 floor staff down to 2-3.

Your premise doesn't work for USA because with the hypothetical American restaurant that only has 3 servers with no runners and those 3 all sharing the workload "as a team" for all tables ... still means those 3 servers want to work for tips. That negates your parent post saying the higher # of staff is the barrier to eliminating tipping.

Instead, the barrier to end tipping in the USA is the inertia of the ingrained culture where servers expect tips and patrons keep paying them.

There are several high-profile restaurants in New York City, etc that tried to eliminate tipping by raising prices and they eventually reverted back to traditional tips.

>Hopefully it is clear how 5 servers dedicated to 4 tables each and backed up by runners can do a lot more upselling than 2-3 staff doing team service.

It isn't clear because those same lowered server count of 2-3 can still ask the same upselling questions... "Do you want desert?" Asking that question isn't mathematically constrained by the # of servers. Instead, it's constrained by the # of tables.