I work as a bartender and on occasion the bar will be slow, or empty, and there is always that person who thinks they’re being cute/funny/ironic when they say something like “Wow! I’ve got the whole place to myself!” or “Pretty busy in here, eh?” or something equally as stupid and pointless. Guess what, knucklehead, we fucking KNOW that it’s not busy and are generally not terribly happy about it; when it’s not busy, we aren’t making money. You pointing that out doesn’t take the sting out of being slow or empty.
If you really wanted to be cool, or funny, call your friends out and take over the bar. Drink, eat, have a good time, tip well, then get home safely. Otherwise, shut the fuck up and stop thinking that is a great opening line.

They’re just trying to make polite conversation with you, you ass. They’re not trying to be an amature comedian.
Ah, the eternal riddle: Which came first, your bad attitude or an empty bar?
Can’t believe nobody wants to hang out at a bar where this delightful person works.
Time you figured out you are in the hospitality business, bartender.
I guess it’s always Happy Hour for this bartender!