Why don't Twisted Transports have methods for receiving data?

Question

I'm reading the following tutorial on Twisted: Tutorial

I've a question regarding what I read in this section:

It says in the tutorial that

Transports represents a single connection that can send and/or receive bytes.

It later said that

If you scan the methods defined for ITransport, you won’t find any for receiving data. That’s because Transports always handle the low-level details of reading data asynchronously from their connections, and give the data to us via callbacks

What does the latter mean? Why aren't there any methods for receiving data?

Answer 1

The use of callbacks is referred to (tongue-in-cheek) as the Hollywood Principle: "Don't call us, we'll call you." Instead of calling a method to receive data, you register a function that you want to be called when data is available, which is referred to as a callback function or just a callback.

Answer 2

A callback is a function which is invoked when the asynchronous activity is finished or ready to notify of some progress. The documentation is describing a behavior in which the creator/caller of something using an ITransport doesn't have to ask for data and wait around doing nothing.