It’s not unusual for my kids (son, 11; daughter 8) to share a room when we have people over for a while. When my mom had her liver transplant, she needed to use my daughter’s room on the main floor right across from the bathroom. We have a couple of bedrooms downstairs that the kids could’ve used, but I didn’t want to exile one of them so they chose to share the room with my daughter on a blow up bed on the floor and my son in his loft bed above. They did that for about 8 weeks and preferred it because my daughter is afraid of the dark, and my son likes to know that someone else is close by, so it worked really well. We’re not rich, but we’re probably middle to upper middle class. It never occurred to me that it might be weird or frowned upon. So, yeah, I’d say it’s really a thing. It might not be what some people prefer, but I really don’t think it’s that strange.
As a side note, whenever we go to India, my kids, my son, my daughter and I all share a family bed, which is really common there. It’s more a matter of practicality than anything else. And if we’re traveling along with my husband’s family within India and we happen to be limited in terms of space, it’s not uncommon for my husband’s grandmother to sleep in the same room (but not bed) with us and for my husband’s male cousin to share a room with his mom and dad. My brother in law usually either sleeps on the roof where there’s one more bed or, if it’s too cold, sleeps with his aunt, uncle and cousin. I find having my husband’s grandmother sleep in the same room way more awkward than having the four of us in the same bed, mostly because I am terrified I’ll snore or fart or something otherwise sort of embarrassing and disruptive in my sleep. But given that it’d be rude for me to pitch a fit and the lady is nearly 90 and can’t handle stairs, I’m hardly going to clutch my pearls and refuse.