Scale uses their pricing page to help inspire people to think about how to use their API. For example, there’s 6 "usecases" spread out over Categorization and Comparison. They all cost the same amount, however Scale uses this as a chance to help people visualize what their API can be used for. Notice how everything on the pricing here is the same cost! They don't just want to explain pricing, but also show you ways you can use their API.
Even though their APIs cost them money, they still give some free requests so you can try it out. The pricing is done per call. Normally bulked pricing is better since it’s easier to forecast financials for both the creator and consumer. However, given that they’re selling actual human time, it probably makes sense to do it this way. There’s no base fees or hidden fees, which is rare for a human-powered API.