In the real world I believe contractors would never stock wire sizes : " 300 / 400 / 700 / 800 / 900 AWG "
Is this true or am I way behind with the modern times. Thank you for your support.
The term AWG ceases to apply for sizes larger than #4/0. After that, the area units of KCMIL are used directly, and the American Wire Gauge scale no longer applies.
A contractor can stock any wire size they see fit, and is available in their area. And at sizes of this scale, I'd expect to see them ordered at the length needed for each job, instead of stocked. Some sizes tend to be more readily available than others, due to market forces of how often it is that they get specified, especially those that are more likely to match the standard OCPD ratings. Since the sizes you listed are in-between the default sizes for each standard OCPD, that is why they are rarer than the neighboring sizes. For instance, 250A breakers default to 250 kcmil Cu, and 300A breakers would default to 350 kcmil Cu, but there is no standard rating of a breaker in between these sizes that would default to 300 kcmil Cu.
For 700, 800 and 900 kcmil, I've only seen these sizes on datasheets for Aluminum. Most datasheets for copper wire don't even show these sizes, and jump from 600 kcmil to 750 kcmil to 1000 kcmil.
