That’s going to vary. Some people are probably just trying to rationalize it to themselves. But some people (and some cultures) have a very strict “penis in vagina” definition of sex. That’s why the word “sodomy” was invented: so that people could distinguish between “real sex” and “dirty stuff that isn’t sex but is sexual in nature.” So if someone doesn’t think oral and anal sex count as sex even when they occur between a male and a female, then they probably won’t think it counts when it’s two males or two females.
That might seem crazy, but it’s more understandable when we realize that most straight people don’t think they have to specify that they had vaginal sex. They’ll just say “I had sex,” and everyone just assumes that means a penis entered a vagina. This sets vaginal sex as a sort of default, which sparks debate about whether anything else counts. I think oral, anal, and vaginal sex are all sex. To borrow a line from sex columnist Dan Savage, they’re all part of the “sex” family, which is why they share the same last name. But a lot of people disagree.