As someone who has actually.owned and operated lots of vending machines of different types over the years, no this isn't true.
You can buy vending machine locks that are keyed the same if, for example, you wanted all 12 machines that you owned to have locks that could be opened with the same key but the chances of that key opening any random vending machine you may encounter are about as good as your house key working to open your neighbor's house... Not impossible but not super likely.
In fact, just yesterday I picked up a vending machine key that it took a locksmith over two weeks to make for me with only the lock to copy it from because I'd lost my original for that particular machine.
I have several other vending keys that I tried (mainly because I was confident that one of them actually was the right key) but none of them worked.
Vending machine locks and keys are actually quite complex and varied.
If you are from Europe, especially German-speaking countries: So called Buntbartschlüssel (literal translation: colorful beard keys) are very popular for older buildings and garden sheds as well as for interior doors in residential buildings.
There are around 70 different types with you being able to spot which one is need by just looking inside the keyhole, there are handy charts for this purpose.
Our vending machine was so old ( and kept outside) that the hinges rusted right out and the door was just hanging there by a bit of the top hinge. So the key was irrelevant. Just thought I'd mention that
Tubular locks are extremely simple to pick. The only reason they're used is because they're cheap and used to protect cheap stuff, like food in vending machines
Some tubular locks are simple to pick and yes a modified bic pen is the poor man's pick but it's certainly not all of them that can be done that easily.