You can be honest, not stopping from your departure to your destination, but that is only you. If one is not honest, stops everywhere, goes to a pub, doesn't keep his distance, comes at the border and says he didn't stop, shows the invoice of the camping or hotel from one or other country, then he may pass without problem.
The good always have to suffer from the bad. It is always like that.
You can come to Belgium, you can take a walk outside, you can go to a pub or restaurant, as long as your common sense works good, there is no problem.
I live in Belgium, I am going to work every day, I speak to my colleagues, I go shopping, and I am still alive and not ill.
It is not the country you go to, it is how you behave yourself opposed to others.
I am a quite asocial person in real life, so I am not going to big meetings, festivals, cinema's...
If I go on holidays, I want to see as less persons as possible.
But not everyone is like that (luckily), and they are causing the problems with the spreading of the virus.
I didn't like shopping in the first place, but now I really hate it, so I am not going to look for new clothes, or just walk in a shop for looking what they have. I now only go to a shop if really necessary, and only for the time needed to do the purchases.
On topic:
I don't really know the regulations about quarantaine if you just pass a country without stopping.
