The vast majority of small/medium customers would rather pay-as-you-go than maintain a fixed cost instance, and it allows Algolia to efficiently pack them into a multitenant architecture instead of wasting resource overhead.
With 4 mio. records and 4 mio. queries I would pay the same. But then at least have 4 mio. queries.
The other way around, if we would just index all 200+ countries in the world and have autocomplete with a lot of visitors we would pay for eg 50.000 users per day typing in 3 letters again $4.000.
Same for us, we offer 350.000 movies with 2 mio. scenes. With Typesense or even Elasticsearch Cloud we would pay 5% of what we would pay Algolia.
24hrs * 60mins * 60secs = 86400
86400 < 50000
QED
The exact small/large label doesn't matter, nor does the requests-per-second.