I don't think it's fascistic at all. Think about it this way - I would like to trade my right to bring a cell phone into group event in exchange for the benefits I receive from participating in a group event without cell phones.

If you don't like that trade, don't make it! But don't deny those who wish to engage in that transaction the right to do so by forcing them to have a "cell phones are welcome" policy.

This is a rock concert. There is no coercion to attend whatsoever. You are absolutely, 100% free to decline this transaction.