What is the Load referred to RS-485?
Absolute maximum ratings should never be achieved. They just tell you when the chip will be damaged.

If you want to know the maximum supply current (to size your power supply) during normal operation look at the "Short-circuit output current".

In practice the current consumption will depend on the total bus load ie. how many devices are on the bus, if they all have 1 unit load (there are transceiver chips that represent 1/4 or 1/8 unit load) and termination type.