That's a pretty broad sweeping statement. Just because people don't do anything with their leaves doesn't mean it kills their lawn and that they don't care about how their lawn looks. In fact, leaves can be good nutrients for the lawn. It really depends on many factors -- every yard is different. I can't speak for others, but for us, we have about 3.5 acres of yard with approximately 25 trees planted in clusters throughout the yard along with some 50+ year old trees along the edge of our property. Based on the advice of our landscape designer, we do nothing with our leaves other than mow over them if we happen to mow the lawn after they've fallen (and this is what we've done for the last 18 years). If the wind creates a pile of leaves that gets "stuck" in a corner of the landscaping or house, we will remove those leaves. The reality is, because of where we live, our lawn actually starts to go to it's dormant/winter state before most of the leaves fall -- we *might* need to do one lawn mowing after the leaves start to fall, but that usually doesn't happen as the grass has already stopped growing. Curb appeal??? I guess I have other things to worry about because I'm really not that concerned about what the neighbors think if we've got leaves in our yard for a few weeks -- I don't need to impress anyone. It's not like our yard is covered with leaves all year round -- it's a month or so...maybe...if the wind hasn't blown them away yet. Our neighbors all have leaves in their huge yards as well so I don't think any of them care that we have leaves in our yard. I actually like to see the colorful leaves blanketing the yard -- that's what autumn looks like. It's a very pretty change after 6 months of plain green grass. We don't have a thick layer of leaves on our lawn -- just a thin scattering of leaves. Most of them blow away (directly into our wooded area or a field -- so no harm to anyone else's lawn if they would care about leaves...which they don't.) within a few weeks and the rest mulch/disintegrate over the winter and the lawn actually looks green and lush in spring. I've never had piles of leaves left in the yard after the snow melts in Spring. We don't really need to do much of anything to get our lawn looking great in the spring -- just the initial trimming/pruning and then mulch every other year. Mother nature takes care of the rest. We don't even need to fertilize the lawn as the leaves take care of that over the winter. People compliment us on our yard all the time, so I know it's not just us who think it looks nice. We actually have a lot of pride in our yard.
If we lived on 4 acres of heavily wooded land and had thick layers/piles of leaves everywhere, maybe we'd do something with our leaves, but we don't have that under our current conditions. I see no reason to waste hours of our time raking leaves that are going to take care of themselves. Obviously people with a ton of leaves in their yard might need to remove them. That's not my yard. Not sure why it matters what other people do with *their* leaves. Also can't imagine assuming someone doesn't care about their lawn if they don't rake their leaves. That's a leap.