Unsuitable?

I'm just back from a few days in Llandudno.

They still have Routemasters there - but only on the Town Tour (and then only when it's not fine enough for the open-toppers).

You can take a tour of the Great Orme on a 1958 Leyland Tiger Cub. . . .

. . . .or, for a fraction of the price,  on an Optare Solo on service 26

The cable trams (same system as San Francisco) run through some pretty narrow streets that would nowadays be considered unsuitable for public transport vehicles.

Although, maybe not, as Arriva service 26 runs every hour in each direction round this sharp bend and up (or down) the 1-in-5 hill on a road that is officially "unsuitable for buses" in two languages!