This pretty much. I make it a rule never to ask waitresses/bartenders out usually because it's their job to be friendly/flirt a bit.
Yeah well this is how I use to feel too but recently I started dating the waitress at my local cafe. I thought she was just being friendly/doing her job and because she is really cute and is also a personal trainer(she has a smoking hot body) I knew heaps of guys would be after her so even though we were getting along really well I didn't think anything would happen.
Eventually she started dropping hints that she was single and then one day I just asked her if she wanted to go out sometime and she said yes
Heaps of guys do ask her out though and some of her customers even buy her presents, including one guy who bought her a book and put $1000 cash inside...plenty of guys leave their business cards/phone numbers under the windscreen wipers of her car and shit like that too.