I agree with the good points made by everybody about using the min/max spec, but I would add that a good engineer understands the part and how it works.

With the LM317 it is an old design linear regulator with power transistors etc, and the high spec of 10mA is required to achieve ALL output currents during ALL combinations of voltage (and probably temperature). It's something like a beta current on a power transistor, the beta spec for "full" saturation of a power transistor might be something like 20, but if you are only using a small collector current you can often apply a much lower base current and use the higher beta that results (say to get power savings).

In a thread here i ran a LM317 as a constant current regulator with only 1.5mA and it seemed to work fine even though far out of spec. Of course that does not mean it would work wiht 1.5mA and all voltages, currents and temperatures.

 

A more expensive LM117 has a max operating current spec that is half the spec of a cheaper LM317 but what if an entire production run had excellent spec's (like the LM117) but they need to supply some LM317s?
Then they mark the excellent ones LM317 and LM117. But you are not told that.