When someone offers to "set up a tab" for you, politely decline!
We were staying at a campground resort which had a pool bar, a small restaurant, and a night club. When we checked in, we paid by credit card and wanted to buy a small gift item from their gift shop. The host said, "I'll set up a tab for you and put the gift on it!"
We have been down this road before, at other resorts, on cruise ships, in bars and restaurants. A "tab" is a really horrible idea. You are giving them your credit card and saying, "just charge me whatever" and later on, if you want to challenge it - good luck! It is particularly problematic when you are staying somewhere for a week or more, like on a cruise ship. Mistakes are made - sometimes on purpose. Servers want to make a quota so they add drinks to your tab. Some crooked guest hears you use your name and then orders drinks using your name and room number. It's been known to happen.
At one campground, in order to "put it on my tab" all you need to do is state your name. In another, they wanted your name and site number - which you are shouting at the bartender over loud music in a noisy bar - anyone can hear the information and use it to charge their own drinks. It is not a very secure system, to say the least. Some cruise lines now require you present your room card, and they run this through a swipe machine and print out a receipt for you to sign. I guess they got tired of passengers challenging every damn charge - but their solution was a bit of overkill.
On one cruise trip we took (and we've only been on three) there were passengers lined up every morning to dispute their tab at the concierge desk. Maybe you can't remember how many beers you drank last night, but when some oddball drink shows up on your tab (No, I don't do shots of Jager, thanks!) you know someone made a mistake. It got to be comical almost - there was one "extra" drink on the tab every day. And there was no other way to pay onboard. Of course, I suspect it works both ways - some passengers claim they never ordered that many drinks, just so they can chisel the cruise line a bit. And of course, the cruise line just deleted the charge without question - it wasn't worth the hassle for them.
The other problem is, of course, that when you say, "Put it on my tab" - particularly after a few drinks, you might forget what you ordered and later on get this huge bill at the end of the day or week. At that point, it may be impossible to challenge some of the charges. Worse yet, the charges may be legitimate - you just forgot how much you ordered. And when you are not pulling cash out of your wallet or even swiping a credit card, well, it makes it a lot easier to spend. The more difficult you make it to spend money, the less likely you are to do it.
This is why little old ladies write checks in the checkout line - and take forever to do it. Or they pay cash and count out the pennies for exact change. Good for them - they're being smart. You're the dumb one for tapping your foot impatiently when in reality you have nowhere to be or nothing else important to do - right?
When you pay cash, you can see what you are spending - and how much things cost. The other problem with a "tab" is that often when the waitstaff puts something on your tab, you don't see the actual cost of the item until you get the bill. Gee, I didn't realize that beer was $15 a glass! When you pay cash, the server has to tell you how much it cost at the point-of-sale.
The resort we were in was reasonably priced - beers were $4 apiece and well drinks were $5. A cheeseburger with fries was $10. Can't beat that! But the charges were done several times - one for the tab, one for tips, one for the gifts, one for membership fees, and one for lodging. It took me a while to sort out and the tab was the hardest part.
And no, there was no error in the tab - and many people would just pay it and not bother challenging individual charges. Hey, it's just money, right? Maybe, but it's my money and it represents my freedom - my ability to live.
When we travel, we usually take a small pile of cash with us - in small denominations. If we got stuck somewhere, thousands of miles from home and for some reason the bank canceled our credit cards (as happened once!) or they were lost or stolen, I want to have enough cash to buy gas to get me back home. And it isn't hard to install a safe in your camper and even in your truck (they make them, and they are not that expensive!). Rather than setting up a tab, I prefer to pay cash - I don't have to do any accounting at the end of the day to make sure I am not being cheated.
I am sorry I let the host set up the tab for us, as it took me about 20 minutes to go through it all and figure out why there were so many separate charges to our credit card (when it was just one tab!). If it had been all-cash, there would be no work to do. And it would be safer and easier as well.
What's more, many servers prefer cash tips - it is undeclared income for them and their boss doesn't necessarily know how much they are making.
The irony of the whole situation was that the host set up the tab to pay for the small gift item we bought. But that was never put on the tab. Rather it appeared as a separate charge.