Many intersections have established paths for walkers, before they put in ramps and curb-cuts for wheelchair users. Especially at old intersections, there are often big posts near the corner--supporting streetlights or traffic lights or street signs. Sometimes they block part of a walkway, and walkers just go around. Sometimes they're beside a 30" wide sidewalk, where walkers hardly notice...but they complicate the problem of putting in a ramp that has to be 40" wide.

I can't know what happened with these particular intersections, because I don't know the exact dimensions. Sometimes "deliberately" putting a ramp off to the side is not so much a choice to keep groups of people apart, as a deliberate choice to put a 40" new construction in 40" of open space (rather than trying to move big heavy objects to make room elsewhere.) If the curb cuts were installed when the intersection was built, rather than doing it as a retrofit, it would just be bad design.