Maybe if you turn your head to a different angle? Squint a little? Tetromino puzzles are easier if you're allowed an extra shape... ;)

I suspect these pages are unedited, as originally submitted by the authors. So if it makes it into the WPC then they might choose a different set of possible shapes...

@uvo and kiwijam

-- You are correct.

The rules of Puzzle types used for WPC from this list, if there any ambiguity has been appropriately modified for final use.