It's a combination, where the demand curve never meets the supply curve at an acceptable price for the consumer.
It could be due to being able to obtain a product cheaper from somewhere else due to lower labor costs (happens due to converging standards of living across the world), and it could also happen that there are alternatives, such as other jobs and/or social security disability or welfare that make doing undesirable jobs need an even higher price point to make it worthwhile.
It could be due to being able to obtain a product cheaper from somewhere else due to lower labor costs (happens due to converging standards of living across the world), and it could also happen that there are alternatives, such as other jobs and/or social security disability or welfare that make doing undesirable jobs need an even higher price point to make it worthwhile.