Because both industries are full of abuse that is mostly directed at women, which fact has been turned into general condemnation of sex work instead of specific address of the factors that directly precipitate said abuse.

It seems to me that when people advocate further criminalizing sex work on this basis they are either dissembling (in the way advocates for professional licensing dissemble that it is about 'protecting consumers' because it is more effective than admitting they are trying to protect their own interests) or simply horribly misguided in how best to address the (genuine) problems you describe.