In an ideal world, retailers in this country can perhaps insist on high standards of production and may even be able to implement reliable checks to control whether the high standards are being met.
Exactly correct. We agree.
But in a world where supermarkets buy a very cheap product like garlic from China which is easily produced in this country or in Spain, there must be an even greater temptation for supermarkets to buy the much higher cost beef from America at the very cheapest price irrespective of the standards used to produce it. How are consumers able to determine how beef from America has been produced without government-imposed classification they are extremely unlikely to implement?
I'm not sure I follow the logic here. Beef from America is much higher cost, so supermarkets are tempted to buy it because of it's very cheap price?
Importers in any country should be responsible for ensuring that imported products meet the standards of their country. Food produced for import-export market is usually produced by larger commodity producers, typically the producer has many satellite farms, the producing company sets standards for the feed used, cleanliness standards, etc. The producer wants very uniform quality, and can't work with farms that cannot meet production quality standards (if quality is excellent at 99% of farms but terrible at 1%, the 1% will drag down the price of the 99%). Any kind of meat production has very narrow profit margins, this dictates strict quality control by the producing company.
The importer, as the customer, has a lot to say about the standards followed and quality of the product. They can dictate that government-imposed production standards are met so that classification standards are attained, verified by inspections.