Why is Doing it bare with only prep a thing?

Hey there, my husband and I recently started to meet other people. I noticed one thing that really shocked me: about 3/4 people only wanna meet us, if we do it without condoms. They claim to have a negative test (always from the actual month lol) but never show it. They often say: no we’re doing is safe because I’m taking prep, you should too! So I wonder why this is a thing… Like even taking doxy prep is dangerous. Mostly I’m just thinking about drug resistent STD which thrive in exact these situations. So can you please enlighten me? Is it a lack of knowledge? Do the doctors don’t inform properly? Or do they just don’t care about personal and public health? Btw, this is one of the studies I found VERY concerning.

https://www.cdc.gov/gonorrhea/hcp/drug-resistant/index.html

Thanks a lot