it is because everyone says binders hurt and compress and break your ribs. when you’re first seeing information about binding, it’s all about how binding is unsafe and will physically hurt. I don’t mean to lecture you, just to give a real answer to the question
and the answer is that by the time someone works up the courage to start binding, they have–at minimum–seen multiple sources of information claim that binding is unsafe and physically hurts, as absolute medical fact. most likely, they haven’t seen ANY information refuting this. at all.
so step one is deciding you need to bind badly enough that you will endure physical pain and potential medical complications
and then you buy a binder that’s most likely shit quality, made from materials meant to compress, barely one step above ace bandages. there are tons of these “binders” out there, sold for very cheap by scammy companies
and remember, you think is is Absolute Medical Fact that this is just how it is. so you’re probably not doing much searching for “better” materials or a “better” company because there is no better. you have absolutely NO conception whatsoever that it could be better
then, even if you do get a quality binder made with good materials, binder sizes are genuinely out of touch with actual reality. I weighed maybe 115 lbs and the binder that fit me comfortably was a size LARGE. I had never in my life been anything less than a small. I started by ordering a medium because I have just-barely-C cups and knew I would start putting on weight with the testosterone and–
I could barely get it on. it was SO tight. any other piece of clothing in the entire universe and I would have immediately recognized “oh hey this isn’t my size”
except binding is unsafe and physically hurts
so even with a quality binder from a good company, because I accidentally ordered a size too small, I still almost ended up binding in a way that was unsafe and physically hurts because that’s what I expected! it was working AS INTENDED!!
it was working as intended
for anyone still reading along, that is the POINT of a lot of information out there about binding. for the same reason conservatives tell you if you’re gay, you’ll die of AIDs, then point to the statistics of all the people who died of AIDs, and fight so so SO hard to make sure there’s no proper sex education to tell you about condoms or PrEP (taken to prevent getting HIV) or treatment afterwards or how your viral load can be suppressed or that it actually can be managed now and isn’t a quick death sentence
I ordered one size up (the large size), and that gave me a binder that fit like a tank top. It has a stiff cotton panel in the front that is just tight enough to press down on my chest, but mostly it just redistributes how the fat sits to make a more even, flat across shape. you can see in the first pictures how the front panel forms almost like a cone, that may not be completely FLAT (it still pushes out a little) but there aren’t any curves or noticeable “breast shape”
my binder doesn’t leave red marks or dig into my skin. the shoulder straps are wide and, again, distribute the weight more evenly than a lot of bra straps I’ve worn before, which did dig in and leave red marks. I think a lot of people also approach binding from a background of wearing ill-fitting bras, bc no one really teaches us about or helps us size those either, so we’re already used to “chest undergarment that hurts me”
the binder I have is safe to exercise and swim in while wearing, it pulls on and off over my head like a tank top, and I can take full and deep breaths while wearing it. I have never been short of breath or struggled to breath from wearing it
binding does not have to be unsafe and should NOT physically hurt. if it does: the materials are wrong (compression) or the size is simply too small