Paying for electricity

Pretty typical for Snowbirds in Texas.

That's been very common in the private parks we've stayed in in Florida once your stay get past the nightly rate. When the rates drop the extra electricity rates kick in.

Common for Monthly rates, especially in Snowbird areas.
Rare for weekly stays.
Almost non existent for daily stays.

When charged, is it flat fee or metered?

None and never done long term or storage.

Metered.

It seems its usually metered when staying monthly. I was boondocking out in the sticks and got water at an RV park that runs on an 85kw diesel generator. Monthly spot $250 plus .33 kw!!! Never cheap to run on generator.

you are paying for the electricity whether they meter it or prorate in to your daily or weekly bill.just seems to sting a little more when they hand you a bill for it

More common than not just about everywhere for monthly/seasonal sites.

Short term, you typically pay much more per night and they typically include it as it's a lot of hassle to check the usage before & after a stay.

A couple campgrounds we've been to had an extra charge if you were going to use your air conditioner. That seems to have faded away a bit - the last time we were at campground that used to do that, the manager said they had upgraded their electric grid and just raised rates a bit.

Otherwise, at most campgrounds we've been to the seasonal sites have individual electric meters.