There Is Only One Official Distributor Of Henkel Laundry Pro
In the United States, Miele North America.
Where or how others are obtaining German laundry products is anyone's guess. However judging by the prices charged they face the same costs as Miele. In fact given that the later imports such a large volume of products to the USA, prices from them aren't *that* bad, it is the mark-up some vendors take that can cause sticker shock. As with everything else, Miele does require a certain MSRP for all products, so vendors try to find "wiggle room".
When Miele first started selling laundry appliances in the United States, there were few if any "low sudsing" laundry detergents available. Tide was then and still is one of the few brands that can equal results of Persil, but it was not suited for front loading washing machines (too much froth). Indeed early versions of Tide "HE" weren't that much less frothing than others, however the recent launch of liquid detergents seems to have gotten things right.
The situation you describe does not apply totally to the United States. In the UK/EU what are called "HE" detergents here are the norm, and have been for ages. Therefore it stands to reason those on that side of the pond have numerous choices.
OTHO "HE" washing machines have only recently began making any dent in the American laundry market, and detergents designed for standard top loading washing machines are the norm. Even when detergents are sold for use in front loading or such machines, they more likely than not are the same formula used in other machines, just with added anti-foam chemicals.
To even the playing field, the detergent market here would have to resemble that of the UK or EU, and that will not happen for several reasons.
One, many Americans still own and would purchase top loading washing machines over "HE" versions. Regardless of government dictates and incentives many simply feel the former type of washer cleans better than the later. They also aren't keen on paying >1K for a washing machine that lasts on average five years before it starts acting up.
Being as all this may, have been getting great results with Tide "Free and Gentle" HE liquid. Removes most all stains including red wine, rinses clean and leaves no scent. Would use it for all loads, but it has OBAs so cannot be used on darks/colours.