I think some distinction might be that the virus can be detected on surfaces for longer than it is actually still infectious. My dated biology knowledge tends to support hours more than days.
That I find hard to believe but of course I could be wrong. Viruses can't exist outside a living cell the same way bacteria or parasites can. They die really fast or almost don't exist by themselves simply because of natures design. Instead, they tend to attach to other bacteria or human/animal cells. That's why influenza and the likes spread from a living being to another, where on another hand you can catch bacteria from any dead matter/surface, etc...
The complicated coronavirus cases, according to latest news, have had septicemia or additional bacterial lung infection of some sort that lead to pneumonia,hence the hand washing to prevent pathogenic bacteria . My thinking is that we can catch coronavirus easily enough from infected people, but as long as that's all we catch, we're in the 80% with mild enough symptoms. Whoever has healthy organs survives despite the lack of native immunity as long as they're also immune to the bacteria the virus attaches to. And we all know these days we have wiped out our immunity to bacteria via antibiotics.
Today I read that 1/3rd of the infected also had upset stomach/diarrhea. Considering that 80% of the immune system is regulated in the gut, it may mean that people with pre-existing stomach issues are also susceptible because of pre-existing live style complications that have led to weak immune system, hence children are generally fine and diabetics and people with hypertension, or any other pre-existing life style condition aren't.
And my last bit on it is on the connection and studies already done on viral infections susceptibility and selenium deficiency, specifically on RNA viruses like the coronavirus. Apparently selenium plays a huge role in the immune response, which one needs in times of sickness. I read a study from 2016 explaining why the Chinese population is susceptible to viral infections due to the depletion of selenium in the soil and thus the population in general, plus the type of diet. Selenium rich foods are eggs, meat, nuts, fish and not bread, pasta, noodles or rice like in China or Italy. From what we're told, both SARS coronavirus and Covid 19 have originated from China.