Incidentally I often go abroad for a weekend and only take the currency of that country. It costs more to use my card abroad.
So you take a car abroad, often, for the weekend, taking only cash? What would happen if you had a puncture?
Or do you manage to rent a car for a weekend out of the three hundred quid, for cash? Neat trick: most rental companies will refuse to rent for cash, but I guess there might be some off-off-off-airport ones which will do it?
But if you aren't taking your car, and you aren't renting a car, why would road tolls or parking charges be an issue?
This is precisely what amuses me about these debates. The construction of spurious "ah, but what about people who..." scenarios which don't make any sense.
People who bring their own cars in this country without any means of payment other than cash don't, for practical purposes, exist, and if the minute handful who do are almost certainly people this country can well do without.
People who travel by plane to the UK for cash and then rent cars in the UK for cash, with no other means of payment available, equally don't exist outside the fevered imagination of those constructing "ah, but what about..." cases.
In exchange for this, we are expected to provide manned toll booths and to provide large numbers of ticket machines which are ripe for vandalism and fraud and require labour to empty and to cash up. And even then, we can construct equally spurious cases of people whose only means of payment is the ten pound notes they got from the ATM.