I am wasting time on Google Earth. I went to La Jolla California and started scrolling up the beach. (Remarkable how steep the hills are there, by the way.)
There is (was) a set of tire tracks on the beach.
In coastal communities, do the police routinely patrol the beaches in isolated areas? Why?
Just a WAG: To track smuggling, drug trafficking or illegal immigration?
The beaches of Assateague Island on Maryland/Virginia’s Eastern Shore are patroled by park rangers (who have police powers). They’re patrolling to protect public safety, just like on the street. I’ve come across people in some really remote beaches - the police can’t really tell where people will or won’t go if the space is open to the public.
I guess I just never thought about it before. Google Earth; endlessly time-wasting.
Yeah, I recalled a story about a police vehicle running over a sunbather and Googled for it – looks like that happens occasionally. I guess sunbathers fall asleep lying down and the police come zooming over a dune without realizing.
Let’s be careful out there!
Sailboat
If by “public safety” you mean the threat imposed by consensual sexual acts, I can vouch for ya. 
In Spain, yes, yes and yes. Actually, the point with the illegal immigrants often isn’t to stop them but to get them to the hospital on time (many arrive half dead).
The tracks could also come from someone from the local government running environmental checks.
Short Answer to OP Title: Because crime happens everywhere.
Answer to OP Post: Because anything (crime, injuries, etc) can happen anywhere.
I feel your pain.
He was actually pretty nice about it and let us off with a warning and a “You should be careful - you’re a long way from help if something should happen to you out here.”
Life guards and park rangers routinely drive around on the beaches. (I live in San Diego.)
We got mosquito avoidance suggestions as we redressed. He was very nice, and told us that it was a routine part of his shift. We were camping at Assateague circa 1980. 
In Jacksonville Florida I witnessed a police SUV tearing down the beach trying to catch up with a guy who was offshore, caught in a riptide. I guess the lifeguards called for backup…
Ours was very nice as well. PM me and we can compare notes on the experience.
“Dear Penthouse Forum…”
Police, Rangers and -if Baywatch was an accurate TV show- lifeguards all patrol beaches. But you can drive a vehicle on some beaches, so tire tracks don’t automatically mean the cops have been there.
You just did it on the wrong beach. There are others, though . . .
If Baywatch were accurate, I would live in California. So would everyone else.
Right, out here it is more likely those guys. Note that some are LEO’s, however.
Aside from the public safety issues, there’s also the matter of asserting some control over the border, trying to combat illegal immigration and drug smuggling. Both the Coast Guard and US Border Patrol have stations here along the southern coast of Lake Ontario.