The compliance costs include the costs of tracking the wheat through the processing chain just in case it's using GMO wheat Monday and non-GMO wheat Tuesday.
I think businesses that sell food products should already track in detail what kind of wheat their suppliers provide.
because they would assume that labels are only for things the consumer is supposed to care about .
No. If I look at the ingridients list of the Thai-Soap it tells me that it contains peas, but it's not something I'm "supposed to care about". I'm not buying Thai-Soap based on whether or not they contain pea's and the obligation to provide that information doesn't imply that the government thinks I should care about it.
Would you favor the idea of putting labels on food stating whether it has any ingredients that were picked by illegal immigrants?
That's like the some US states requiring taxes for illegal drug sales. I don't think that trying to enforce labeling is the most straightforward way to deal with something that's illegal.
I think businesses that sell food products should already track in detail what kind of wheat their suppliers provide.
Why? They know it's wheat. Why should they be able to track arbitrary characteristics of the wheat? It's like asking them to track which wheat is grown on Tuesdays, or which wheat is grown by Jews. Their system wouldn't be set up for it.
the obligation to provide that information doesn't imply that the government thinks I should care about it.
Containing peas is a subcase of a general requirement "list all ingredients". I...
Basically: How does one pursue the truth when direct engagement with evidence is infeasible?
I came to this question while discussing GMO labeling. In this case I am obviously not in a position to experiment for myself, but furthermore: I do not have the time to build up the bank of background understanding to engage vigorously with the study results themselves. I can look at them with a decent secondary education's understanding of experimental method, genetics, and biology, but that is the extent of it.
In this situation I usually find myself reduced to weighing the proclamations of authorities: