Surely 2 and 3 are risky given you're still going to work (I appreciate your circumstances mean you have to).
2. If one of you have the virus, you go back to work the next day and pass it on to all or most of the people on that building site given you yourself say you can't follow the social distancing measures as it's impossible. They all go home. They pass it on to their relatives and anyone who they want to meet, even if it is another 5 people. And the cycle continues. The reason that has been stopped for now is to eliminate the risk of spreading it, which is what the main aim is, surely?
3. Similar principle as point 2 applies - how do you know you or that person you meet doesn't have the virus? Don't forget people can be asymptomatic. It's not everyone that has it immediately shows virus or immediately needs intensive care in a hospital.
So no, it's not all about the money although I admit that probably plays a big part. And so it should. Wanting to keep people healthy and also not wanting the economy to get fucked over more than it's ever been (or even more than that as time passes) are not mutually exclusive.