Most opamp specs have a minimum, a typical and a maximum value. Each opamp is different even if they have the same part number and same manufacturer.
The datasheet for the TL072 shows
A graph shows the typical voltage loss with different load resistor values. With a +/-15V supply and a 200 ohms load resistance then the output voltage is typically only about 6.2V so the typical output current is 31mA. An IC with a weaker chip will be less.
With a +/-15V supply and a 2k ohms load resistance then the typical output voltage is about +12V so the typical output current is about 6mA.