The vast majority of employees in the EU are not part of a union, it is around 10 - 15%. They get protection trough legislation from times unions were more common though.
Unions make sense for artists since the broad availability of art and entertainment is often hit or miss. Not the best works always win and if there is considerable success, income can get extremely high while others struggle to get by. Especially educational works do get paid poorly. These are essential services compared to another upper middle class manager from a consumer perspective.
At least in Germany you don't have to be a member of the union to benefit from their negotiations. About 50% of employees work under a so-called "Tarif" contract, terms of which get negotiated by unions.
Unions make sense for artists since the broad availability of art and entertainment is often hit or miss. Not the best works always win and if there is considerable success, income can get extremely high while others struggle to get by. Especially educational works do get paid poorly. These are essential services compared to another upper middle class manager from a consumer perspective.