On the stability of the virus on surfaces, here's a fairly recent study:
https://sci-hub.tw/https://www.ncbi.nlm.nih.gov/pubmed/32182409
The virus was viable after four hours on copper, 24 hr on cardboard, and 48-72 hours on plastic and stainless steel. However, the amount remaining of the original amounts applied was greatly reduced in the latter cases. The half-life was 5-6 hours., which means that after one day only about 5% of the original amount would remain.
The authors don't address this, but the stability would also depend on temperature (this study was run at 21-23 o C, basically, room temperature). Virus on some surface outside in the heat--particularly metal, which absorbs heat much more than say, plastic or cardboard--would degrade faster.
But it's reasonable to ask, how much virus is going to be on a surface? Someone who is positive doesn't have the virus on his hands, unless he coughs into his bare hand constantly. Or maybe picks at his nose, puts a finger in his mouth, something like that. Some virus floating in the air from positive people coughing or just breathing will get on a surface, but not very much, not in a very concentrated fashion. I'd think that asymptomatics, pre-symptomatics, or people with mild symptoms are even less likely than people with strong symptoms to have much virus on their hands. Finally, also keep in mind that however much virus might be on a surface, someone touching it only picks up some of it, and of what is picked up, only some of that is transferred to the face, and ultimately to the mouth or nose.