That belly in the line is exactly the kind of thing a laser will never catch because the laser only cares about level, not straight. I had a guy in his seventies lean over my work one time and tell me my courses were wandering about a quarter inch over a 12 foot run, and I had checked it twice with a four foot level. Turns out my level was fine but I was letting the mortar push the brick just enough to drift, a tiny bit each course, and after 20 courses it shows. Any tool only tells you what you ask it, so a straight edge and a string line will keep you honest in ways a laser cannot. That old guy saved me a callback and probably a bad review. Sometimes the best tool on the job is somebody standing back far enough to see what you stopped seeing.

Checked one of these last month on a 2017 with 95k and the cap looked fine, no cracks at all. Maybe it's a climate thing or how hard people crank the cap down when they change the filter. I've seen guys reef on those things way past snug and that's probably what splits the seam more than age. Not saying it doesn't happen but calling it a guaranteed fail at 80k feels like a stretch. Two cars in one shop doesn't make it a pattern either, could just be bad luck or the same quick lube guy overtorquing both.