Many of them fear raising their entrance fees because their audience might stay away. Renting a car is very expensive in Europe and hotel rates are astronomical. Instead of charging for a room like in the US, in Europe there's a charge for each person in the room. Since this money has to come from the talent-buyer that books a band, the hotel can really be a burden on his or her budget. As for advertising and promotion of a tour goes, there are so many different language areas one need to advertise in and thus a lot of different magazines to reach the customer.
Cooperation can save a lot of money.
Bluegrass music suffers from the negative image that country music has in many countries in Europe. We have Hollywood and Nashville to thank for that. The general opinion is that anyone can pick up a banjo or guitar and belt out John Denver's Country Roads. Despite the fact that you and I know that bluegrass is something different than country music, the general public associates bluegrass with the same negative image they have when thinking about country music. As a result, bands often find themselves with the dilemma of either dressing up like Roy Rogers and face the abuse or not get the job.