Irresponsible, sociopathic. Spanish health authorities should know better than to let this happen. The bands playing should be ashamed.
Rapid testing is only about 45% effective in *asymptomatic* infections. Which presumabbly would be everybody at the concert. They will miss at least half the people infected. Barcelona has an R0=1.21 and a prevalence around 10%. 500 people will be infected, at best 250 screened out (not realistic IMO). The 250 will infect another 312. In close contact, hours-long concert conditions most likely a whole lot more.
Helping the variants get more traction. It would have made more sense if they'd made it based on proof of vaccination, and offered on-site vaccinations. Rapid asymptomatic testing is almost pointless, and masks in a concert situation is almost as pointless. Dumb and narcissistic humans.
"Thanks for coming to the peasant experiment... I mean, show! Hope you're not one of the 312 that's going to get covid!"