Montana 650 behaviour vs Zumo 595

[TwoUpTourer]

When I import a track into my Montana, I get a nice pink line on my map, and whether I follow it or not, the Montana doesn't care, it's up to me to follow it, or not. It doesn't care that it originated from an underlying Google or OSM map, it is just a line. I love it. Nice and simple.

But on the Zumo 595, the freaking thing has a mind of its own, having a fit if I dare to wander off for a while and demanding I return to where I deviated so I can re-join the straight and narrow. Why, when it is a track and launched using the Track app, should it exhibit these routing type behaviours, trying to tell me where to go. I thought the whole point of a track is that it is a dumb line, with no smarts attached?
Is there something I'm not configuring on the 595 to make it act dumb?

Lastly, the 595 is mostly unreadable in sunlight, unlike my Montana, has there ever been a fix for this?

[Fred D.]

Turn off automatic recalculate and it will not alter the route.
You can purchase certain screen savers that help with glare and improve sunlight
viewing.

[TwoUpTourer]

What I'm trying to understand is why recalculation should operate on a track at all. It should only be routes where recalculation functions.