I agree with SAMouzon, natski, boilerplater and Gotta Speakup that all of these concerns are significant but solvable.
The suggestions of 5' setbacks if the lots are wide enough, maintenance-access easements if they are not, sounds reasonable and according to SAMouzon, they often work.
The problems natski describes sound like a matter of property lines not being clearly marked and of clear, simple rules not being laid out and explained beforehand to all parties (developers, builders and homebuyers) and enforced every time they are violated. Most homeowners are smart enough, and leery enough of lawsuits, not to encroach a slab or fence on someone else's land (or to lean a shed on a neighbor's wall) if they know where that land starts.
1. Mark the boundaries clearly and set cut/fill, drainage, pest/flammable debris control, encroachment and access standards in simple, no-uncertain terms at the outset.
2. Tell every concerned party clearly when they first get involved (such as requiring sellers/realtors to explain the rules in plain English to every new homebuyer and require both seller and buyer to sign a one or two page copy of the rules with an "I have read and understood..." statement, minimum one copy to be retained by each).
3. Smack down hard on the first several violators.
Most builders and homeowners will get the message and avoid problems, and the stubborn or careless who don't pay attention and cause problems anyway will be fewer in number and easier to deal with--signed documents greatly simplify enforcement actions and court cases, if the documents' intent is clear and enforcement is consistent.
Not one of the concerns listed in this thread is truly intractable, and not one really supports any kind of universal "Case Against Zero Lot Line" homes, a phrase which falsely implies that such things are inherently, incurably bad and ought to be banned. Gotta Speakup is right that more options in housing and neighborhoods is a good thing (and I might add a very American thing, the kind of thing that increases freedom by enabling more people to shape their lives their own way, because frankly, one size does not fit all--urban, suburban, or rural--, never has, and never will.)
Thread redirect: What are some of the specific solutions you guys have come across or implemented to these issues? In particular, what has worked, and how did it work.