That would be hard to get data on, because alcohol is mostly legal and meth and heroin are mostly illegal.

So you have a huge confounder: it seems likely people who are willing to do illegal acts, are more likely to become unemployable.

So if meth was legal, and alcohol was illegal, the situation might be reversed.

(I'm not saying this is true, but to make your statement you'd need to carefully exclude the possibility of this effect.)

Btw, heroin and other concentrated drugs are popular partially because we banned comparatively milder and bulkier alternatives. Eg opium ain't as hard as opium, but it's just as forbidden, and its bigger bulk makes it less profitable to smuggle.