Eh, it doesn't work like this unfortunately; pay is never a mirror of the dangerousness, the utility, or the dirtiness of the job. I would say that usually it's the contrary: the more essential a job is, the less it is paid.
Walmart requires a consistent level of output which they hope can be maintained by keeping truck drivers happy with high pay. Other trucking companies can afford to have some drivers leaves and thus pay them less because they have some leniency for delays which Walmart cannot/will not tolerate
Dirty and dangerous work attracts fewer workers.
High-utility work is worth more to the employer so there will be more job offers.
When you see dirty, dangerous, high-utility work that pays poorly, it's because there's a ton of people who are willing to do it.