He's implying the same laws that say you can't drive trucks on a Sunday, also restrict other labor, or make it uneconomical (e.g. having to pay mandatory overtime for weekend hours performed).

He's wrong anyway, there's no ban on general trucking on the weekends in Belgium, only oversized loads. He is right about strict labor laws, you'll barely find any open stores on a Sunday, besides restaurants, bars and some other forms of entertainment.

But yeah, God forbid you can't go to the European equivalent of a Best Buy on a Sunday, so some retail worker can enjoy their weekend.