Fronting loans to suppliers isn't even remotely in the same legal or regulatory ballpark, unless Apple owns a meaningful stake in those companies. Fronting loans is extremely common; what Musk is doing in commingling, and at the scale he's doing it, is extremely rare today (it used to be a lot more common pre ~1970s or so, the vast expansion of financial regulations and increase in the SEC's powers, have limited it in recent times).