I cannot speak for all restaurants and all counties, but as noted in my comment, I'm currently abroad in Russia (St. Petersburg), and while it's true that the s

I cannot speak for all restaurants and all counties, but as noted in my comment, I'm currently abroad in Russia (St. Petersburg), and while it's true that the servers generally don't check in for anything else other than the bill once the food is served, it's also true that they'll be there pretty much immediately if you ask for them or signal them. A simple gesture and they'll be there pretty much as they are able to be. To me this seems the right balance of service and respect of privacy. As an aside, my experience is that most restaurants also don't really do refills so much as "another drink purchase", so it kind of makes sense in my mind that they're not keeping an eye on how much liquid you have left - if you want to spend money on another drink, you'll let them know. I think this is just a cultural difference as well as a different way of business. To me having a server constantly checking in on how much is left in my glass or interrupting to pour a drink is more disruptive than a quick gesture to catch the server's attention and signal them over.