Seriously. What's up with that plot device? Is it just a way to get fictitious right side/wrong side of the tracks kids to mix in a public-ish space? Let me present the evidence:
1) Beverly Hills 90210, Summer 1991
Brandon leaves a sweet gig at the Peach Pit to earn some extra summertime dough at the local sun spot for the zip code's hoi polloi. Makes sense. Loves Nat, loves the Pit, loves his job. Why not give that up for a chance to be a cabana boy?
2) Saved by the Bell, Fall 1991
Clearly, the Saved by the Bell writers went into hyperdrive when they saw the preceding summer's Beverly Hills 90210. Bell upped the ante, though, by having Zack, Kelly, AND Slater get jobs at the club. Kelly, if memory serves, was a lifeguard in a ridiculously small one piece. The lifeguard flotation thingamajig she hauled around was bigger than her torso. I'm sure she saved many, many lives that summer.
3) Dawson's Creek, Fall 2000
I've searched in vain for any kind of clips or stills from any of the Season 4 episodes, but, just so's you know, Joey gets a job at the Yacht Club's restaurant and mixes it up with an uppity uppercrust fella. The only (free) clips available were stunning examples of Kevin Williamson's hyperarticulate banter between Joey and Pacey. Oh, the banter, the unbelievable, unbelievable banter.
4) High School Musical 2, Fall, 2007
I haven't seen this little phenomenon yet, but I have nieces who are nuts for it. Anyway, this sounds like Bayside all over again. Main male hottie gets a job, then make sure everyone else gets a job, and a tiny girl is a lifeguard. I mean, I know suspension of disbelief is necessary, especially for musicals, but could we just acknowledge that an ninety pound girl is not going to be able to accomplish these feats?
So, anyway Hollywood, enough with the teenagers-in-country-clubs-theme!