I am not a Boing Boing spokesfungus or anything; but (speaking on my own behalf) I'd be inclined to judge the situations differently depending on the openness of the data (for clarity' sake: while I would prefer 'open' as in 'permissive license' on other grounds, it would be perfectly possible for quite restrictively licensed map data, so long as the restrictions don't preclude viewing the ingredients, to fall on the right side of 'openness' for this purpose).
Trusting a map vendor to build a 'red zone/green zone' map according to its own internal criteria is not unlike trusting censorware software that attempts to hide its block list. You are left guessing as to what motives and considerations were stirred into the product and are now being treated as operational realities.
Being able to observe the process doesn't free you from the risk of working with lousy data; but at least you can see how the sausage is made, and even tailor the weights assigned to various ingredients to suit your taste.
Again, this is, strictly speaking, orthogonal to open-as-in-open-source: a proprietary vendor willing to show you enough of the raw data, rather than just the product, would also fit the bill; but open-as-in-open-source assures that, while getting inside access to proprietary datasets is frequently treated as either impossible, or something for which you pay extra, possibly a lot extra.