Venues face need to co-promote shows to reduce dark nights.
These days, if venues want the date, they're often finding it necessary to pony up to book the show.
Increasingly, buildings are taking on the promoter or co-promoter risk, communicating directly with agents to stay on the radar when tours are being booked.
The math is simple: There are more buildings than there are tours to fill them. The impact of festivals buying loads of talent and "major market only" touring exacerbate the situation.