In fact, you can print from iPhone without AirPrint. A special casing is a printer whose manufacturers have created certain applications that manage to print directly, without going through AirPrint. But more generally, it also includes printers that do not have a wireless section, you can do so by putting it between the computers that act as a bridge between iOS and a printer connected via USB.
So that's why you can print from iPhone without AirPrint. Here are the three most common options for this type of printing.