Those perks look like taxable income to me, though I don't know which government she will answer to in terms of her tax liability. If she took that deal for a job to be performed in the US, then I believe she would be guilty of tax evasion. That the work is to be performed in another country may change that analysis. I don't know.

Were I in her shoes, I would also want to know why the employer wants to do it this way. If it's all legit, then I see no ethical problem with it. The comments about Swiss work permit law look like they are on point.

The best advice I could give would be for her to spend some of her own money on at least two lawyers - an American tax lawyer and one or more Swiss lawyers familiar with their tax and employment laws.

As for the thread title, I don't see it as an ethical question. It's more of a legal question. That's usually the same thing, but not always. This arrangement looks ethical to me, unless it involves deceiving the government or some other third party. As between the parties, they are both free to enter into whatever arrangement they like. Their both grownups, so to speak.