FYI: If you hate In 'n' Out's fries, ask for them to be double fried. They'll do it and then they'll be like the normal kind of fry everyone else has. It just means waiting in that long-ass like even longer.
The fact they're not frozen isn't what makes them not crispy; it's the fact they don't par fry them. Frozen fries are just par fried before freezing. If you fry them twice, you get the same texture. You can make McDonald's style fries yourself at home from fresh potatoes by frying them twice, with a rest period in between. The only other thing that significantly alters the flavor is the kind of oil you fry them in.
This is probably also true. When In'n'Out conspicuously puts the potato slicer in view of the counter, they're really making a statement that limits which ways they can cook the fries.