IMO it's not the pay level that motivates people to " turn up on time and work as they should for pretty good money."
Obviously some people are more reliable and better workers than others. But the chances are they would still be better workers and more reliable if they'd been taken on at a different rate, higher or lower.
Pay level is unlikely to be the answer.
They've agreed to the rate on taking the job so it must be acceptable.
If you're having motivational problems with a series of workers, you need to look at what's wrong with the rest of the package.
Poor working conditions are a far more likely de-motivator, leading to lack of commitment. Particularly if it's worse than they expected from recruitment. Sort that out, and you sort your workforce motivation.
I suppose there are just too many thick people out there lol
Yet smart enough to get past your selection process ? lol