My parents were a bit like this - although not to the same extent as the OP's, it has to be said.
When I was 10, we went to Morocco - the first family holiday where it was just me and the parents, as my DBs were both out of the family home by then. On that holiday, several fully grown men offered to buy me from my father for X amount of camels, Y amount of camels, Z amount of camels... every time we went outside of the hotel as a family. Even now, 30 years later, my parents still laugh about it. I didn't find it funny in the slightest, though. I found it deeply frightening as a child and, now that I'm an adult and a mother myself, I find it deeply worrying that my parents both laughed and joked along with the strangers who had approached them in the streets to offer various camels for me!
My eldest DB wasn't amused when we returned home and I told him this... but then, he also wasn't very impressed by the fact that I used to escape the hotel each day (because I was bored and the parents were too busy sun-bathing or sleeping to actually watch/occupy me) and run around the small town unaccompanied. Fortunately, there were some kindly shop-keepers opposite the hotel whose wives/mothers used to keep an eye on me, and let me sit in the cool of their shops and watch the bartering between the tourists and the shop-keepers, and the hotel's security guards, after the second day, gave up returning me immediately to my parents and let me drink coke in the hotel bar... but, my goodness, as an adult, as a mother of two who have been 10... it makes my blood run cold as to how lucky I actually was during that month!!!
That was the one and only holiday I took alone with the parents. After that, I went with my oldest DB and his girlfriends, and was taught that when you're responsible for a child/young teenager, you watch them. But perhaps, my parents simply didn't understand that I was a child who wouldn't sit quietly in a hotel lobby for hours on end and do nothing. Because on previous family holidays, I had DB1 to watch me - who was 14 when I was born, and always the one I remember fishing me out of the sea when I got into trouble, or off mountain's goat tracks, or playing endless games of 'tag' with me, or football, or cards, or... well, just generally parenting me.
So, yes; your parents behaviour was odd, OP, but yours isn't an isolated case, I'm afraid. I suspect there's quite a lot of us whose parents just didn't seem to know how to interact with their own offspring on foreign holidays...