Something not talked about here is that there's a finite number of seats that can be sold for all the tours in the year.
At a smaller scale, look at Broadway productions. There are 41 "broadway" theaters in New York, each with between 500-2000 seats performing 8 shows each week. Ballparking because I don't have the exact numbers, that's a total number of tickets you can sell of under about 350,000 tickets for all broadway shows that can be sold each year. Even if you include all the touring and local productions of shows in cities, there are not enough theaters to meet the demand for live musicals and plays (and while locally, shows will underperform and not sell out, and there are periods of downtime between shows changing, it's still capped).
Now these massive tours are limited in a similar way. There are only a few dozen arenas that can seat tens of thousands of people year round, and only so many nights they can operate. But unlike those shows, a single production team can't "own" a venue for months at a time. So they need to tour, which is about the most expensive way to get a production of that scale off the ground. Moving a production and staffing it throughout a tour is so expensive that guaranteeing the endeavor is profitable is still difficult - many of the "biggest" tours with sellout crowds across the country have been financial disasters.
Basically my point is that the issue isn't just in fairness in ticket sales. It's lack of venues. Which makes sense. If we had cities operate like Las Vegas, and have venues that put on high profile shows for months at a time with residencies, the access to the shows might be (paradoxically) improved despite being hyper local. If you can guarantee a low risk/profitable production and rely on people traveling to the show (which many do! look at broadway - people can and do see shows affordably with the highest cost being the plane ticket) then the problem might be better mitigated. Or maybe not. I'm not an economist, but the point is that the supply problem goes a lot deeper than people trying to buy tickets at the same time.
At a smaller scale, look at Broadway productions. There are 41 "broadway" theaters in New York, each with between 500-2000 seats performing 8 shows each week. Ballparking because I don't have the exact numbers, that's a total number of tickets you can sell of under about 350,000 tickets for all broadway shows that can be sold each year. Even if you include all the touring and local productions of shows in cities, there are not enough theaters to meet the demand for live musicals and plays (and while locally, shows will underperform and not sell out, and there are periods of downtime between shows changing, it's still capped).
Now these massive tours are limited in a similar way. There are only a few dozen arenas that can seat tens of thousands of people year round, and only so many nights they can operate. But unlike those shows, a single production team can't "own" a venue for months at a time. So they need to tour, which is about the most expensive way to get a production of that scale off the ground. Moving a production and staffing it throughout a tour is so expensive that guaranteeing the endeavor is profitable is still difficult - many of the "biggest" tours with sellout crowds across the country have been financial disasters.
Basically my point is that the issue isn't just in fairness in ticket sales. It's lack of venues. Which makes sense. If we had cities operate like Las Vegas, and have venues that put on high profile shows for months at a time with residencies, the access to the shows might be (paradoxically) improved despite being hyper local. If you can guarantee a low risk/profitable production and rely on people traveling to the show (which many do! look at broadway - people can and do see shows affordably with the highest cost being the plane ticket) then the problem might be better mitigated. Or maybe not. I'm not an economist, but the point is that the supply problem goes a lot deeper than people trying to buy tickets at the same time.