Why prostitution can never be legal like other jobs

Let's image a world where prostitution is legal in the way other jobs are legal. For example, it could be legal like being a secretary is legal or being a hair dresser. Once it it fully legal then companies can hire prostitutes as employees. They could job interview and advertise for employees and hire them with professionally written employment contracts and have yearly performance reviews. The employees could get good health care and benefits. What is the problem? Every dude in a small company that is going to hire a secretary is going to have the job description be answer phone, take dictation, arrange meetings, blow me on request, ensure office supplies are ordered, water the plants, and handle bill payment. Since prostitution in entirely legal then you can write jobs that require work performed while being a prostitute. Then if there were no people who wanted the job because it was disgusting they could apply for foreign workers to fill the position since no citizens wanted the jobs.