It depends what you count as free solo. In the alps you definitely can book tours without a rope, that involve low grade climbing, that most not mountain people would consider as free solo. And it is the same principle there. One wrong step and you fall to death. And people do. But experienced guides can minimize the risk, by going routes, the client can manage.

Knowing the Swiss attitude a guide would refuse to help someone get over their head. This is also called passing down techniques through oral tradition.