Hekapoo is the designated authority to give people scissors, and has some degree of supernatural awareness and control over their use.
She's also definitely not the strict/lawful type who would hold everyone who wants a pair of scissors to some uniform "fair" standard of trial. She saw Marco as some uppity fleshwad abusing her stolen property, and definitely didn't expect him to pass his trial.
Also, while the Magic High Commission has styled themselves as the interdimensional authority on magic and enforcers of law, they are definitely not impartial. They collaborate directly with Mewni, specifically the Butterfly family, to the extent that several former Queens have served on the commission. It's very possible that dimensional scissors have been created and given as part of political settlements, or even gifts, between the Butterfys and other royal families. Ludo's clan is/was on good terms with the Butterflys, they might have earned their pair as part of their settlement in the Mewman-Monster Accord, or as a reward after the implied past conflict between them and Toffee's clan.