The visual trick behind legacy fonts
In a legacy Nudi font, an ASCII value such as P may be drawn as a Kannada glyph. The page looks Kannada only while the exact font and mapping are available. To software, the content is still a sequence of Latin-era codes.
This was a practical publishing workaround before broad Unicode support, but it tied every document to its font encoding.
Why copied text becomes unreadable
When legacy text is pasted into another app or shown with a different font, the Kannada shapes disappear and the stored ASCII symbols become visible. Search and spell-check also operate on those symbols rather than Kannada words.
ASCII is not a bad standard
ASCII remains a foundational encoding for basic Latin text. The problem is using its character slots as private labels for Kannada glyphs. Unicode solves that mismatch by assigning Kannada its own standard range.