Anywhere where you exist on top of someone else's service is basically killed by a 30% margin. To use an example I worked on a while back, dynamic Minecraft server hosting: Taking advantage of the fact that most small servers need much less than 100% uptime, you realize that if you dynamically spin up and down these servers, you can offer substantially better use-based pricing. You're basically an AWS reseller in this scenario, so there's a hard floor in what you how much you can charge, because VPSs cost money, but you're competing against "leave the server on 24/7", which is your upper cap. Unfortunately, unlike those "Up 24/7" servers, you need a good way for your customers to spin the server up and down. A phone app seems like a good way to do that, until you realize that 30% of that revenue potential would be forked over to the app stores.
100% AWS uptime, at cost -> your competitor's price
10-15% AWS uptime -> your marginal costs
50-60% AWS uptime -> maximum price you can really charge while differentiating yourself on price
25-32% AWS uptime -> subtract your costs and google's cut from that maximum price
When you start factoring costs like customer acquisition, it starts getting very, very tight. 30% profit can make for a pretty healthy business, especially in businesses where your prices and costs can be predictably coupled. But a business with a 30% profit margin that has to pay 30% is a failed business.
What you're describing is a service that has an accompanying app. In those cases, you can just take the Netflix route and not offer the subscription on the app at all (only through the website), and voila, no 30% charge. Given how little of the value proposition for your service lives in the app itself, neither app store is going to have a problem with that plan.
100% AWS uptime, at cost -> your competitor's price
10-15% AWS uptime -> your marginal costs
50-60% AWS uptime -> maximum price you can really charge while differentiating yourself on price
25-32% AWS uptime -> subtract your costs and google's cut from that maximum price
When you start factoring costs like customer acquisition, it starts getting very, very tight. 30% profit can make for a pretty healthy business, especially in businesses where your prices and costs can be predictably coupled. But a business with a 30% profit margin that has to pay 30% is a failed business.