The simple fact is that we have made concessions to "need". Grocery Stores have been open the entire time, and trust me while some people do attempt to socially distance, many do not. And it isnt an age thing, I have had all ages, all races, genders, etc. come right up to me and stand way, way too close. Everyone makes mistakes, but the simple fact is that our world is not setup for 6 foot distancing, almost no hallways or aisles are wide enough to accommodate that and it would be prohibitively expensive and wasteful to try and make it work. We can try and make things "one way", but who is going to walk all the way around an aisle and back down again when you forgot something 5 feet behind you that now has someone standing at?
Is a shutdown constitutional? I would think so, but it probably needs some type of "emergency" declaration to go with it. Not actually sure states or Federal Government did that, but since it was left in the states hands (despite some talk from Trump he actually did not shutdown any areas other than Federal Government installations). So did your state declare an emergency? Did they give the governor the power to close things? Probably not, but honestly it is just paperwork.
I cannot see a 2nd shutdown even slightly working, the simple fact is that more people are going to get sick. The point of the shutdown as I saw it was to stop it from being society-destroying, and it did that, but it was never really going to not allow for the virus to continue to spread, just not a plague.
Opening things back up will cause increases in infection rates, it is unavoidable. If you think the person near you should have a mask on then get away from them, if you believe that it is foolish of them (it is, clearly) then eventually they will of course get theirs. I am too old and too tired to fight with someone over something as stupid as wearing a mask, I dont like it either, when it bugs me I step outside and breath easier again or I cut my trip short. It isnt difficult, I am not going to try and tell someone who is obviously too arrogant and stupid that they are arrogant and stupid (this does not apply to people parking in handicap spaces, I will say whatever comes to mind to them every time I see it until the day I die, and if I wouldnt be punished I would destroy their car).