I believe they can’t publicly display price, but others can.
It’s an agreement between them and the manufacturers to not publicly post sale prices.
If the manufacturer didn’t want them selling it for less than the original price everywhere, they would easily figure out to PM them for the discount price, and then stop selling to them.
Manufacturers don’t care, because they’re still making their money. They just want every business to have a fair chance at sales.
Businesses like SportbikeTrackGear, Riders Discount, Biohazard Cycles…etc all do it.