Your grocer on your side of the border grows produce in highly regulated fields where the soil is tested, the fertilizer is tested, the machinery is tested, the transport is tested, and the workers are your neighbors who are paid like you. Across the border, that grower is pooping in the fields, nothing is clean, the machinery is decrepit, and they're paid subsistence wages.
Your grocer wants to sell across the border to your foreign counterpart but that government says no, they can only buy from their own grocers. But that government wants their grocers to also be able to sell to you. Your government says okay, and then they sell their groceries for $50 because they don't inspect the soil and manufacturing process, and they don't pay their workers the same wage.
-PJ
How many restaurants have you dined at again after getting botulism? Let the cheap goods enter America. I love saving money. All year long I enjoy fruits and vegetables despite the fact that most are not grown here or in sufficient quantities.
In the particular cases you cite even consumers know to wash their fruit. Once it was discovered that the Chinese had made sulfur laced drywall, nobody would buy Chinese drywall and the American mfgs thrived. No government intervention needed.