Because that’s not a structural issue. Take a look at a lot of these kinds of things, you will find over hangs are actually incorporated into builds because that helps masonry in certain situations. Such as this even, if the slab goes past the stones, that is a water ingress and will make these guys move/deteriorate more easily. (Edit: it is not necessary in this build. I would have cut the stones down to fit the slab, but it’s not really anything to worry about on your end). Look, I’m not saying they did a great job, but they are landscapers, full stop. Hire a mason for masonry work (I say this as a 20 year stone mason that has spent time working for landscaping companies in the past). Landscapers slap shit in as fast and dirty as possible (gotta buy the boss a new truck or excavator each year, after all). They do not have the knowledge or tools to do stone masonry, if they did they wouldn’t be landscapers. I’m not faulting you for this, just giving perspective. I wasn’t even allowed to dress stone as a landscaper, they see it as a waste of time. I was just as surprised as you when I found this out. This was from two different companies. I do landscaping like this as a side gig now in my own business, my company’s name is Brimstone Masonry and Landscaping. The work you received would not fly if one of my guys did that. But my guys are masons, and wouldn’t do that. This is perfectly functional and is not going to fall apart. My biggest gripe, to tell the truth, is that messed up cut against the house. That’s not ok for a mason or a landscaper.