Also, it only says that they should have fins and scales ... the ease or difficulty of removing the scales is not actually a thing in either Leviticus or Deuteronomy.
It is also possible, indeed probable, that ancients didn’t recognize that shark hide is composed of what amounts to teeth. That means the relevant question is if they could have viewed these as extremely fine scales. The texture is very different than, say, the skin of a dolphin which would definitely be recognized as not being scale based.
Tuna have scales.