I think that it is because of the fonts. Not any font can represent any character.
This is what I get in python3:
http://www.fileformat.info/info/unicode/.../index.htm
https://www.fileformat.info/info/unicode.../index.htm
This is what I get in python3:
>>> print('\xf0>\x90\x1f\xde0') ð>Þ0See the missing characters - "\x90\x1f"? They are unprintable.
http://www.fileformat.info/info/unicode/.../index.htm
https://www.fileformat.info/info/unicode.../index.htm