I don't know if there was an actual law, but certainly our "frituren" had a bad reputation as far as the quality (freshness) of the fat is concerned.
Part of the problem was that their income-tax was partly based on the quantity of fat they bought. Not really an incentive to refresh it regularly.
This is no longer the case. The consumer magazine "Test Aankoop" regularly tests the quality of the fat, and the results are quite OK now.
By the way, the best frituur in the world is in my hometown, Antwerp. Said in full objectivity, of course!
Where's Pardalis? Somebody needs to stand up for the rural Quebec frites wagon. Ubiquitous for years, they're getting hard to find, but they make some of the best fries/frites in the world.
They, too, re-use their oil for weeks and or months. They also pre-cook the fries at a lower heat, and then finish them later at top heat. Makes for an awesome snack, even a meal.
"Cat Stee-may, all dress, pwee duh freet see voo play"! That's how I memorized how to order in
Quebecois when I first arrived in Montreal in 1970. Actual spelling would be more like ... Quatre 'steamie' all dress, pui deux frites, s'il vous plait.
"Quatre "Steamie" (4 steamed hot dogs, don't knock 'em unless you've tried 'em - they're awesome) ,
"All Dress" is similar in Anglo-Canadian, "all dressed" i.e. "with everything on 'em, and "everything' in Quebec is mustard, cole slaw and pickle relish.
"pui deux frites, svp!" = "and ummm, two orders of fries/frites/chips.....
Catsup optional but white (not malt) vinegar preferred.
Music to my ears! Ambrosia to my tastebuds!