As far as any program was concerned the TTY was just a serial port, and it couldn't tell the whether data coming in was from keyboard or paper tape reader.
Yup, that's why they were such useful devices! Even if you were ending up with inefficient storage (punching ASCII vs. binary, or expanded BASIC source vs. tokens), it was built-in.
https://www.youtube.com/watch?v=qv5b1Xowxdk
As far as any program was concerned the TTY was just a serial port, and it couldn't tell the whether data coming in was from keyboard or paper tape reader.