This is because it's actually not allowed to use IQ tests as a screening mechanism for most jobs (you need a valid reason and "software engineer" probably isn't

This is because it's actually not allowed to use IQ tests as a screening mechanism for most jobs (you need a valid reason and "software engineer" probably isn't good enough to justify the liability). By using algo questions they can select for something that might correlate very well with IQ, that also makes sure the candidate has real coding knowledge, and which has much less liability