Nearly ten years with my wife; lots of 'unencumbered' anal and no problems. And when I say lots, I mean it's vitually the only place she wants it. Not that I'm gonna object to that...
Never used a condom with an ex and we did a lot of anal. Never any UTI problems for me. For a guy, ejaculating cleans out the urethra. Technically, a guy can get a UTI from vaginal sex just as easily.
As does urinating after ejaculation - which is why this is an extremely common urge - a natural bodily defence mechanism.
Now THERE'S a porn scene... Ugly guy with monster penis grunts and collapses onto woman's back, dick in ass, and says "I'm coming" Woman: "Leave your cock in there and pee in me, you fucker!" Woman then voids cum+shit+pee to the camera. lol..........
The secret of not getting UTI's is as easy as Pissing afterwards. If there are any bugs, they get forced out and not in. Like I say, common sense is not that common.