I think coding is different for two reasons - and please do excuse me, because while I've _done_ physical work, I don't do it for a living, so I'm coming at this slanted:
First, with physical work, you're doing, well, physical work. There's a correlation between physical activity and mental acuity, and, as you mention, you can take out some of your stress out on productive labor (if I do that, I have to buy a new mouse). You also have a balance between the physical and mental side - I'm not sure if there's a corresponding mental equivalent to muscle memory.
Second, you can 'outsource' some of the modeling to the actual physical object - the work you're doing has a tangible component, so you don't have to keep the entire thing in your head. That part, to me, is the most draining aspect of coding - I've gotten much better at structuring my code so I can compartmentalize most of that away, but when I'm working with older code or other people's code, I've basically got to have a very accurate representation of the entire program in mind the whole time. That gets really tiring really fast.
I think one of the other big differences, though, is that I can screw up an awful lot more than you can and get away with it - if I completely arse up a section of code, I can go back in and redo it at basically zero cost. If you arse up a floor, well, now we need to buy the raw materials for a new floor. The corollary between experts and amateurs mostly holds between construction and coding - give an idiot enough time and eventually you can have either a house or a program - the difference is he'll cost you an awful lot more trying to build the house. That breeds a level of patience and caution which, frankly, is probably better for one's outlook on life in general.
Anyway, again, sorry if I seemed to demean physical labor - I really didn't intend to. Like I said, I've seen enough experts in action to know the difference isn't in the hands.
> I'm not sure if there's a corresponding mental equivalent to muscle memory.
Have you ever driven to walmart, or work, or your girlfriends (someones) house when you was slightly distracted when driving. You don't drive dangerously, you're not swerving of being stupid like if you was drunk or distracted, you're just not thinking and you end up going the wrong way or doing the wrong thing. There's been a couple of times in the morning when I've accidentally changed the time on the microwave, because I always used to have to hit the timer button before putting in the time. Now I don't, but on autopilot I can somehow manage to find 'time' on a different keypad layout and change the time to 1:30.
I agree with the second, having a tactile object to work with seems to free up a lot of the cognitive ability for the task at hand. Although, when I was doing electrical work you often needed that mental model to know where wires were running, so stepping into someone elses job (especially when it was done wrong or poorly) was a major head-job.
> I can go back in and redo it at basically zero cost
That's why I write fiction, because as a professional career it's only loss of time that matters. Thankfully in my job (vinyl siding) my materials are fairly cheap, so waste isn't a huge concern for us (but a good worker always minimizes it, like unless you're confident you use a piece that's already garbage to make a template rather than wing it on a new sheet) because our company gets paid for our reputation and how presentable our jobs are (there's a big aesthetic difference between done and done properly).
> Like I said, I've seen enough experts in action to know the difference isn't in the hands.
That's in all jobs, I've seen my fair share of talentless doctors, etc. (At 15 I called a doctor out wrong when I self diagnosed psoriasis, the hallmark is scaly skin that pin-prick bleeds when scraped and I had it and I had psoriasis, but that doctor couldn't admit he was wrong to a 15 year old)
Note that I've never even got close to driving on the wrong side when abroad - only after I return home.