You can recover from excessive food and sometimes drugs more reliability than a lot of SH methods. One friend damaged their nerves badly enough through cutting that they ended up killing themselves over it. (the pain and disability, both were probably going to be permanent) These are more shocking and quickly progressing outcomes from the outside perspective of folks who don't SH like myself. It has an appearance or at least a guise of being more urgent and (like you said) without the more relatable upsides of food or drugs.
I suppose, and I don't deny that SH can lead to problems. Just, nowhere near the level of food/alcohol/cigarettes. I mean, countless people die from emphysema or cancer from cigarettes. Has anyone ever died from secondhand SH? Countless people have gotten cancer from secondhand smoke.
Also, cardiovascular disease is the number is the number one cause of death for Americans. Heart disease is completely caused by diet.
Before covid, I heard that according to research, obesity had caused more cases of cancer in the US than cigarettes for the first time ever.
Round up all the people who've been harmed enough by SH to end up in the hospital (or been killed by it), and the healthcare system won't notice. Round up all the people receiving medical care from smoking, obesity-related problems, or diet-related cardiovascular disease and the hospitals of the US and UK will suddenly not have any problems from being overburdened. To say nothing of drunk driving problems! Self-harm usually affects the self, and to a degree the family members. It's nothing compared to the grief that drunk driving has caused, there are entire organizations lobbying for laws about drunk driving such as MADD and DADD (mothers/dads against drunk driving).
Each of those issues - smoking, obesity, drinking - cause far more problems for society (have destroyed far more lives) than SH. SH has the shock value, but if an American or Brit had to choose to banish one thing to best help eg American society, to banish smoking, alcohol, obesity or SH, I do hope they wouldn't choose SH.
I imagine society or at least, our governments make more money from people who eat crap or smoke/ drink as a coping mechanism. Maybe it's because they do end up with so much profit/ contributions from the companies that make these products, that we are more or less encouraged into using them. You wouldn't get adverts for razorblades to self harm with! Not to excuse it though. It's obviously still bad to overconsume.
Both my Dad and I are overweight but, that doesn't stop him making jibe remarks about other people's weight. It always really annoys me because I think it's quite possibly because they are unhappy in some way and, they're comfort eating as a result. I look at them and see pain/ pity whereas, I suppose for most, they just find it disgusting.
It's an interesting idea though. I suppose some self harm- so long as it doesn't become addictive, too extreme or become infected, I suppose could well be healthier than other things.
It is definitely weird the way we will more or less stand back from a person drinking or eating themself to death. Respecting their right to choose but, not so much self harm.
Maybe because people can relate more to the mindset of wanting to overindulge on food or alcohol. I imagine many will be aware of the endorphin rush. I suppose they may just have less of a reference point for wanting to cut or hurt themselves. Not to excuse them though.
Oh my goodness, I am the same!!

When I see overweight people, I think to myself that maybe they're just sad / bad at processing stress. So, sometimes actually I view a larger waistline as a measure of how stressed someone is! (though, people don't just overeat due to stress or even unhappiness ofc) So yes, I will look at overweight people and feel bad for them too, and wish they were mentally in a better place. That is crazy, never heard of anyone out there who thinks the same, but well I'd be the first to say human nature is rather universal. If one person thinks something, than millions have / will do so too :)
And for so much in life, "follow the money". In the US there are powerful lobbying groups to help keep the prices of junk food low, but there's no 'big broccoli' to lobby for subsidies and tax breaks for those farmers, unfortunately :( I did read a study once many years ago that said the majority of US food subsidies end up going to junk food, also there are various articles about how impossible it is to change food subsidies due to lobbyists etc. (And lobbying ofc is legalized bribery)
I also look at addiction as addiction. This could be addiction to food, gaming, SH - whatever, it's gonna be a problem. I remember chatting with one lady once (overweight, worked as a cashier in a supermarket) and she said that food addiction for her is the worst because you
have to eat, but don't
have to drink alcohol or smoke cigarettes. I feel like I was lucky to be raised being told things like processed foods are addictive, the more processed foods we eat the more they encourage the appetite etc. Working in a supermarket, ringing up all the junk food people are buying, and having a problem with food addiction though - it just struck me as such an unfortunate situation :(