The opening band has one of the worst jobs in live music. They play to an audience that is there for someone else, often in a venue that is not yet full, without the production support that the headliner receives, and for a fee that rarely covers the cost of getting there. They are also, historically, one of the most reliable mechanisms for breaking artists who go on to significant careers.
The economics of the opening slot have changed as the touring industry has consolidated. The major promoters, Live Nation and AEG in particular, have significant influence over which acts get access to support slots on major tours. The process is not purely merit-based. Managers and booking agents with existing relationships to the promoters and headliners have structural advantages that newer acts without those relationships do not.
For the audience, the opening band is often where the most interesting musical discoveries happen. The artists who become important to people are frequently encountered not on their own headline tours but on other people’s tours, in venues that were already going to be full regardless of what they did. The stakes are lower for the audience, which sometimes allows for a more receptive kind of listening.
There is a category of artist that exists almost entirely in the opening slot economy, touring continuously without ever headlining major venues, earning modest fees that add up over time, building a loyal audience without ever breaking through to the next level. Some of those artists are fine with this. Some are not. The music industry has no particular mechanism for distinguishing between the two or for directing attention toward the acts that deserve more of it than they receive.