Two reasons.

I think /u/trem gives a reasonable statitical explaination. But it likely goes farther than that. The reality is, these days it is generally considered impolite to start a conversation with a stranger without pretense, and especially so to start a conversation with a woman with romantic intentions. The zeitgeist of our time is that women, by default, are not interested in men’s advances, and that making an advance on a woman for no reason other than her physical appearance (which is all you can know before approaching) is chauvinistic. Thus, almost all intelligent, pro-social men have been trained not to make advances on women they might be interested in in public. So who are you left with? The dumb, not-forward-thinking, idgaf crowd. The kind that spend every night at the bar, and then don’t care if anyone thinks they are a trashy peice of shit. And so that’s who approaches you.

The second reason is probably something about the vibe you are giving off. Reading your post here, and a few of your other comments on lemmy, I get the impression that you are walking around with an expression like you have a smear of shit under your nose. Like, I get that you aren’t interested in these men - but the way you say it, you sound like a very judgemental person who believes she is better than everyone else because she doesn’t eat fast food or something. And the problem with this vibe you are giving off is that it is going to repel the guys you want to attract - healthy, ambitious, intelligent, nice guys who want a healthy, ambitious, intelligent, nice girl. Maybe they interact with you a bit and think “oh, she’s judgemental, I don’t want to date her.” Or maybe they simply see the default look on your face and say “hmm, she looks pissed - I bet she’d yell at me if I tried to talk to her.” The girls who get lots of attention from attractive guys are the ones with golden retriever energy - they love meeting everyone, which means the attractive guys feel less nervous about striking up a conversation and asking them out. It reassures them that, even if this girl isn’t interested, she will at least be nice about it.

I suspect what you’re finding is that the kind of men who make amorous advances aren’t the kind of men you’re interested in, and the kind of men you’re interested in don’t make amorous advances. Have you tried amorously approaching a man who you’re interested in?

Not sure, if you’re actually looking for an explanation or rather just want to rant and/or hope for dating tips, but maybe still helpful to be aware of:

With your specific expectations, you’re somewhere to the far left or far right, whichever way you want to read it.
For example, this graph could be applied to alcohol consumption, with 0 on the left and lots on the right. Then you’re on the far left.

The Y-axis shows how many people exist in that range. There’s some median alcohol consumption, which is going to be in the center of this diagram, where most people are. At 0 alcohol consumption, there’s very few people, because it’s an extreme.

Obviously, this simplifies a lot. In a real survey, there’s probably actually somewhat of a bump at 0 alcohol, because certain religions prohibit consumption.
But yeah, in general, you’re hoping for relatively many extremes, so the number of people that match that are quite low. You will naturally get magnitudes more romantic interest from Average Joes, because there’s just magnitudes more of them.

As somebody else already said, try to find groups that naturally attract folks from the extremes that you look for, like outdoor sports groups.
Online dating, as problematic as it is, can also be rather good at finding very specific extremes.

The outdoorsy athletic healthy men are too busy exercising at the gym to hit on you.

unhealthy, cigarette, alcohol, junk food men sounds like an unsuccessful clone of Teenage Mutant Ninja Turtles.

How are these guys supposed to know that without approaching you?

We want to ruin your life too.

There are more of them that are single than healthy men. Finding your person takes time and effort, but it is worth it.

Maybe you’re putting out junk food vibes? Like you have an aura of dorito dust and Marlboro smoke?

Where’s OP in the comments?

I don’t know. Are you a beer?

Cause healthy good man already had woman

Maybe try joining a running club or something more suited to what you’re looking for.

Because that’s the majority of us. Gotta do something fun when every day is a nightmare.

Hang around healthy men more.