Likely because they have custom pricing based loosely on how much business value they create for the customer. E.g. if a philatelist wanted to scrape stamp catalogs, and if an industry-specific analytics platform wanted to scrape a directory of prospects - you'd want two different prices. Otherwise, you'd either 1) leave stamp enthusiasts out in the rain, or 2) leave a whole lot of meat on the bone w/r/t enterprise pricing. There might also be a consulting upsell!
Eh, that seems like a non-problem. The solution to me is to leave stamp enthusiasts out in the rain. If your SaaS product can provide a lot of value in enterprise companies, $500 a month is not a lot to ask. And many people just want to see the price of a line item if it's a productized service so they can go back to someone higher with a purchase request.
When I was last working inside an organization and reviewing vendors for a product, it really left a bad taste in my mouth when they had "Ask for Pricing." I get it, my consulting work is basically Ask for Pricing, I understand the business strategy. But it's such a headache to sit through bullshit product demos for multiple vendors over a few weeks just to hear that their pricing structure is way out of line.
There is this idea that a lot of companies have, where they're more "professional" or conversion-optimized by removing public pricing and putting everyone through a sales funnel. But that concept only works if 1) you have a great product and 2) you have a great sales team, capable of making my time to failure in the conversion process fast and painless. Every company thinks they have this, but they almost never do. I really don't think you want to optimize your business for keeping stamp enthusiasts happy.
Why?