People regularly test black/gray market peptides in labs for both heavy metals and sterility (USP 61 or 71 I believe). The production of something like Testosterone/anabolic steroids is completely different has higher risks of contamination than peptides which use recombinant DNA or solid phase peptide synthesis.

That video is literally about anabolic steroids not peptides. Not to mention there was 0 testing labs in 2012 that users could send their items to, to get tested while there is many now a days. Back then in 2012 unless you had a friend at a University lab that knew analytical chemistry you were out of luck to get anything tested.

You aren't wrong about a lab in China cutting corners, having quality issues and low quality control standards but people don't care if they see 10,000+ people using peptides for decades without a single complaint about infection or real problems.

"is producing something that normally costs such a high amount" the cost has very little to do with the chemicals themself, the cost is about recouping R&D costs and having a 90% profit margin.