I've had Diamond status with IHG for several years, and like the free breakfast benefit. It's usually straightforward - you choose it as your welcome amenity, give your room number when entering the breakfast area, and that's it. Not so at the Holiday Inn where I'm currently staying in Mexico.

At this hotel, you get a unique voucher at check-in for each day of your stay. You then need to give that voucher to the breakfast staff. Then, before you leave, the staff bring you a bill for $0 which has "service not included" stamped on it. You're asked to write your name and room number, and there's a space for you to enter a tip amount.

I was a bit surprised by this, so had a closer look at the T&Cs on the back of the breakfast voucher and it says "gratuity not included". In other words, the hotel is expecting you to give a tip to the staff with your "free" breakfast. In hundreds of IHG stays I haven't seen this before, although admittedly most of my stays so far have been outside of North America.

Is this a common thing in Mexico/North America? Or just a rogue hotel?