That’s actually not accurate. There’s a number of places that don’t have Lifeguards and, often beaches are set up as county or, state parks passing the costs to either the county or the entire state.

I grew up in a beach town. The main thing that prevents “free” beaches is home rule. I put free in quotes because someone has to clean the beach and, maintain them and, pay for Lifeguards etc. So take a town like Sea Bright or Monmouth Beach both have a small population year round but after May it doubles and then on weekends can sometime triple. Beach fees or, parking fees pay for maintenance Lifeguards part time cops and anything else that has to do with the beach. There’s actually an auditing process that the towns have to use to justify the amount spent on costs associated with the beach vs. the regular operation of the rest of the town. If it’s discovered that the towns are overcharging the people who use the beach and using the extra revenue for taxpayer relief the state can attempt to recover the extra money and force the town to adjust their fees. Often, you’ll see beaches in towns that are free to enter but, have a parking fee that’s because the towns can use the parking revenue more liberally than just a straight beach entrance fee.