Exactly this. The human-factors-engineering take is that these should be mutually exclusive:
- a driver should be able to brake if a person falls suddenly (streets)
- a person is isolated from/ is incapable of falling suddenly into oncoming traffic (roads)
It's the same reason highways are fenced off, extended to streets and roads. A big part of the problem is America's reliance on stroads: too fast to be hospitable for non-drivers, insufficiently isolated to protect non-drivers.
