Where about in the world, except for China, Australia and New Zealand, do imported cases make a double-digit percentage of all cases? Even in countries like Greece, where prevalence levels have been low and testing rates have been high ever since the beginning, imported cases accounted for less than 10% pretty much every day over the summer. The elephant in the room is what's going on within the country. Wherever breaches of the safety rules occur, infection rates go up. Quite unfortunately, this often happens on private premises where there's nobody to enforce any rules - and the caution of the hosts goes out of the window rather quickly.
As for some degree of unrestricted foreign travel being allowed during a lockdown within the country, that's becoming increasingly common. Israel were the first country which went into a full-blown second lockdown while allowing its citizens to travel without quarantine to a list of safe countries including Greece, Bulgaria and Croatia. Needless to say, many grabbed the opportunity to spend the lockdown period at the beach rather than stuck at home and almost all flights out of Israel during the lockdown got fully booked quickly. Now something similar is happening in Europe. The borders of a number of countries enforcing major lockdown restrictions have not been closed and are unlikely to. However, inbound tourism doesn't need a border closure to go into hibernation under those circumstances as nobody in their right mind will go on a leisure trip into a country where a curfew is in force and pretty much everything except for farmacies and supermarkets is closed.