I am still struggling with this one. Like @Anonymous says, it's impossible to impose restrictions on people when they are outside of the home and how could you count on them to tell the truth?
I think @Anonymous is right in that establishing a rapport with guests and getting a sense of how they might behave is more important than ever but, even then, you never really know until they arrive and even then...
Right at the beginning of lockdown I had two guests stay who had both booked before the restrictions came in and the calendar was blocked. Both were long-term, locals, who found themselves temporarily homeless due to lockdown. Both were working from home the whole time and only going out briefly to either buy groceries or go for a walk or run. They followed those restrictions, no problem.
HOWEVER:
1. I noticed guest number one did not wash her hands when coming back to the house. Before moving out, she mentioned she would come and visit us next week. I had to explain why that was not a good idea in the middle of lockdown. I think she was offended.
2. Guest number two told me before booking that he had been in quarantine for three weeks. It later transpired that no, actually, he had just been in lockdown like the rest of us, mingling with those he was staying with and leaving the house, and had only been in the country for nine days, before which he had been travelling all over the place. If a guest wants the room, it's quite likely they will distort the truth! He then started travelling again as soon as it was possible and told me that he would book again in May because everything would be 'back to normal' by then. So, neither guest seemed to fully appreciate the situation.
3. Now restrictions have eased a lot here and there are many things you can do in terms of going out and seeing other people, but you are still supposed to social distance in most circumstances and wear a mask in some. From what I can see, a lot of people are not sticking to this, even my own friends.