I've only seen a few airlines weigh it, mostly budget carriers which I avoid flying these days. I mostly travel in F or J and they rarely weigh for those cabins even if they do for Y. I have seen Qatar and Swiss do it. My carry ons are always heavy, because I typically put anything expensive that I don't want to risk in checked which in my case is usually heavier stuff like shoes or handbags. I also usually have 1-2 changes of clothes in mine in case they lose/delay my checked bag. Which has happened more times than I can count. Even with a lightweight polycarb case it will probably be over the weight. If airlines want to be strict with carry on weight, they should be more reliable with checked baggage. In fact, I wouldn't even need to bother with a rolling carry on if they were reliable.