Stayed in far too many hotels to count over the years...alone and with Lady IP. Not once while ordering room service over the phone have I ever been asked how many guests would be eating what I ordered.
I travel for business at least 12 times a year and have stayed at 5 star hotels on numerous occasions. I’ve been asked, especially at the more expensive ones.
Multiple reasons here...the least offending is the number of place settings needed; towels, pillows, etc. Hotels are in the service industry and want maximum comfort for their guests. Especially a full-service hotel and casino. AND Especially for their high rollers. Knowing the guest count means they know what to expect from the room.
The other is that the reservation has 2 guests staying in that room so the default guest services count is 2.
Another reason is the hotel needs to keep a record of the occupancy of rooms and the hotel in general for liability, safety and record keeping.
This receipt indicates to me that there were 2 people on the reservation, not necessarily just for dinner.
How else would they know how much silverware to include?