AFAIK the 'Waiting for resources' status is used whilst the Async Server has not yet picked up the Async job for processing. Once the Async task has been picked up and started it would show 'In Progress'. So if the Async task was waiting on a database lock on an entity record it would show as 'In Progress'.

Because there are only a finite number of threads available to the Async Server, then those pending other tasks would then be left in the 'Waiting for Resources' - but those tasks are the not actually the ones waiting for the entity record database lock.