So, if you're out and about, and they arrest you under some charge I can't imagine, they throw you in a crowded jail with 25 other people?
The issue is that there are TONS of loopholes in these orders.
People in essential/critical industries are still going to work. People who need to go to the grocery store, the bank, etc can still be out and about.
I believe that nothing in the order precludes me from setting up a meeting to transfer my kids from my ex-wife per our custody agreement next Friday... (But I'm still looking!)
Heck, the one that occurred in the Bay Area said that walking, running, hiking was all still fine as long as appropriate social distancing was observed. So frankly if I wanted to go hiking this weekend I'd be fine.
Basically nobody in power wants to "enforce" this. The idea is that by setting the order, people will get the idea that it's not just a suggestion, and they'll modify their behavior because they realize it's serious. The bulk of people staying home except when it's absolutely necessary to go out is a hell of a big step in the right direction.
If it were to become an enforcement issue, it would be on businesses flouting the rules, not really on individuals.