What you quote can be taken as countering your point about where the problem lies. Trafficking women and 'breaking' them is crucial to (European) prostitution, but is itself no 'marginal activity', but a criminal industry, one bent on profit and growth to boot. As you quote, the situation of women working indoors (women supposedly with minimal protection) is hardly better. And as the Cologne example shows, offering good protection won't be used by the overwhelming majority for various reasons. I'd say prostitution in general cannot be separated from criminality (even if single prostitutes could get into 'normalised' situations).

_{*Lunatic*, n.
One whose delusions are out of fashion.}