In my country of 8 millions (Switzerland), about 340'000 people commute to Switzerland each day to work [1]. These people come from Italy, France, Germany and a bit from Austria. A lot of these people do important work, such as working in hospitals, administration, services, ...

Locking down the borders completely would just have been impossible. You would be suddendly in need of nurses and doctors. Sometimes, more than 50% of the personal in bordering hospitals are cross-border commuters [2]. Yes, you could discuss on how Switzerland is taking advantage of "cheap" labor from neighboring countries, but it does not change the fact that for Switzerland, closing completely the borders (with 14 days isolation) is just an impossible task.

[1] https://www.bfs.admin.ch/bfs/en/home/statistics/work-income/... [2] https://www.swissinfo.ch/fre/fran%C3%A7ais-et-italiens-dans-...

In Europe, a lot of people (including many essential workers) commute across a border every day to work. What do you do with them?