"It's the sort of thing that prompts local authorities to put in traffic restrictions, entirely reasonably,..."
Not "entirely reasonably", not reasonably at all. What causes authorities to put in restrictions is the endless complaints of an entitled few, not concern over improper use.
"...because residential streets are designed for access, not throughput. And if they get misused, then that's bad."
BS. All roads are designed for "throughput", some for higher throughput that others. No road, however, is optimized for throughput since it's speed limit is set intentionally too low, at least in the US. Driving on a public road to get somewhere is NEVER misuse.
"Anyway it's a classic case of "this is why we can't have nice things". People will abuse the residential roads and eventually the authorities will intervene."
No, we can't have nice things because a few ruin it for others. The few in this case are not the drivers, it's the residents who think that public roads are their private property.
"Then those abusers will whine and the locals will grumble a bit about the restrictions, but not that much because of the reduced traffic on unsuitable roads."
The way to "reduce traffic on unsuitable roads" is to fix the roads which are intended to handle that traffic. No discussion of that though! Who cares just so long as the residents get the roads reserved for their use only.