When you press CTRL and a letter or symbol at the terminal, shift doesn't do anything (unless it's required for the symbol, as in CTRL-@). The code that gets sent is the same either way. Emacs users have to be wary when setting custom keybindings because GUI Emacs can see the difference but terminal Emacs can't.

Likewise, ALT just sends ESC assuming you're using the standard US keymap.