I hope you can get somewhere with them.

I wouldn't worry about bugs. I've open up boxes with pasta in them that had meal moths, cornmeal with weevils, chicken feed (that I use as litter) with grain mites, and so on. I still use those products and all of those were one time incidents.
Now if you opened up something and it had roaches in it, you have full right to pitch a fit and never buy that brand or from that store again.

Those are something that come from dirty environments, where as your grain pests typically don't - they're just something that can get into grain.
On a related note - some of those pests, like meal moths are really really good at getting into things. They do like dry pet food and occasionally people will find them in it. They have a short life cycle (being moths) and the larvae can chew through thin plastic (including ziplock bags). If you get those in a bag, it's probably not the food manufacturers fault.