It is not true, has never been true, and probably never will be true that all genders and all sexual orientations are equally at risk from HIV. I don't at all doubt that government health material has emphasized that HIV infection is a risk for everyone, not just for gay men, but I do doubt that it has ever said both sexes and/or all genders and sexual orientations are equally at risk.

Setting aside blood transfusion and related risks (e.g needle sticks, needle sharing) because, although very significant early in the pandemic, they are relatively unimportant as a method of transmission at the moment, one look at the relative risk of sexual behaviors will tell you that there is a certain group of people which is considerably more likely to be infected by HIV if exposed to an HIV positive person.

Taking insertive penile-vaginal intercourse as the index risk, since it's the lowest meaningful transmission risk at 4 infections per 10,000 exposures to a known infected source, relative risks are:

• Insertive Penile-Vaginal Intercourse: RR = 1
• Receptive Penile-Vaginal Intercourse: RR = 2
• Insertive [Penile-]Anal Intercourse: RR = 2.75
• Receptive [Penile-]Anal Intercourse: RR = 34.5

Note that the absolute transmission risk is arguably quite low. Even if you are the receptive partner in penile anal intercourse with a partner who is both HIV positive and not on suppressive drugs, the risk per sexual contact is only about 1.4%. This is, of course, why frequency and diversity of sexual contacts is also a major epidemiological factor.

You can see that there's one specific sexual activity here which is an order of magnitude riskier than the others, which is being the receptive partner in penile-anal intercourse. This activity is much, much more common among men who have sex with men (MSM) than among any other group of people. It's absolutely true that there are both men and women who have contracted, and will continue to contract, HIV from participating exclusively in vaginal sex. But the risk of any given encounter is much lower, and combined with the fact that men who have sex with men tend to have much more frequent sex and much more diversity in sexual partners, it's hard to imagine we will ever live in a world where HIV infection and AIDS diagnosis are not both grossly disproportionately common among MSM.