It's strange to me that the job of a lifeguard is entrusted to teenagers across USA, where I'm sure most of them do not receive any rigorous training in matters like these and the majority of them do not look like they'd be strong enough to save a person anyway.
At no point have they made me feel safer for being there, unless they're doing it as their full time job.
My friends who were lifeguards received pretty thorough training, I think.
The certificate takes 6 months of study and includes a full first aid education, as well as water-specific first aid, what does drowning look like, how to swim against a rip tide, how to tow someone who is either dead weight or thrashing or larger than yourself. They have to be able to swim 1 km with a time limit. They have frequent training drills and go for refresher courses every year or two. And the pay is quite a bit better than normal kid jobs pay. Think 10-12 per hour for a grocery store or fast food job, and 17-19 per hour for lifeguarding.
I only know two or three friends who have done it, but they are fairly impressive people, to me. I can't speak for all lifeguards of course, but I always felt pretty happy with the supervision of my 17 year old friend Michelle, for example, when the 6 kids in my care at summer camp were splashing in the lake.
I think they are doing quite a good job considering the vigilance it takes. The beach near me has mostly teenagers lifeguarding, and there has been 30k rescues over the years, with zero deaths while lifeguards were on duty. I do not hear of many drownings anywhere with lifeguards on.
I imagine it depends on the pool and beach area. Most notably, the older management staff that overlook the lifeguards.
Anectdotal, but I was a lifeguard in my Highschool years nearly 2 decades ago. Scrawny at 5'9 140 lbs. However, we spent a lot of time training and practicing rescuing people. We made sure all our staff could individually rescue someone that is 250 lbs+ across the pool, tread water holding bricks over our heads and swim respectably fast, trained how to scan the pool so that there are overlapping eyes and no blind spots on each area. We were all CPR certified (however we deemed the lifeguarding a failure if you've already needed to resort to CPR due to drowning). We spent hours practicing loading a victim with a spinal injury in water onto a backboard (spinal backboard procedures), and even had EMS stop by to train us on first aid. Refreshers on procedures and training were done quarterly.
When not at the side of the pool, we're cleaning bathrooms. Good times for minimum wage. Even saved a couple of kids that wandered too far off into the deep end during summer. No one even noticed they were drowning.
I hope at least some of this provides you with some trust to your local lifeguards even if they are young.
At my local pool in the UK they are picked from the swimming team. When I was in the team (many moons ago) we were doing 60 laps for a warm up. That's about a mile. So they are good, strong swimmers.
Interestingly CPR success rate is really low (around 20% I seem to remember.) We're all told that. After a couple of breaths into the patient, if they don't start coughing up water and sit up, then you're not likely to save them. So the qualifications don't matter so much as speed, strength and attention.
I don't think many ocean swimmers know how dangerous the ocean is (to judge from people's accounts here and other times this issue has come up). So many people might not be able to be responsible in the way you suggest.
I wonder if there's sometimes a risk compensation problem from the presence of lifeguards -- forms of "I don't need to be so careful, the lifeguard would save me".
You've been downvoted, not sure why. But this is true. Lifeguards mainly tell people not to go in where it is dangerous.
Like I said in my previous comment, if you get into trouble it is very hard to see you let alone get out to you and save the day. You are responsible for your own safety.
We used to red flag the beach (no one in the water apart from local surfers) then at the end of the day take the flags down and get ready to go home. Every time some idiot would go in for a swim... as if the flag was the thing that made the sea dangerous.
Lifeguarding isn't taken seriously in America. Go to Australia, there are lifesaving clubs all over the place, kids join them and learn this stuff early on.
At no point have they made me feel safer for being there, unless they're doing it as their full time job.