I'll wager that a big part of the shifter/mode switch getting sticky or immobile would be not only salty roads, but the amount of time spent immobile. Mine spends more time wet than dry, but being in constant use, the friction parts stay polished.
However, this weak point was designed into the car, apparently to reuse the ICE gearshift assembly. If Mitsu had incorporated the mode switch into the gearshift housing and simply run the signal wires back, there'd be no moving parts exposed to weather.
Greasing those shifter contacts before storage rather than after would be a good move.
2012 i-SE "MR BEAN" 96,000 miles
2000 Mazda Miata EV, 78 kW, 17 kWh
1983 Grumman Kurbwatt EV,170 kW, 32 kWh
1983 Mazda RX-7 EV 43 kW 10 kWh
1971 "Karmann Eclectric" EV 240 kW 19 kWh
1965 Karmann Ghia Cabriolet