Most "enterprise" companies are paying full API costs. The subscription deals are only available to consumers. If you want enterprise levels of control over how your staff are using the models you need to pay up.

Big companies actually are paying published API rates, Anthropic and OpenAI models are desirable enough that there is very little wiggle room to negotiate. It's their way or the high way. Same with things like "safety" filters and (for Fable) mandatory data retention.

Most of their revenue comes from customers pay API pricing.

Those individual subscription plans you get as a consumer are not what their big enterprise customers are using.

Those plans are cheap so you, as an individual, can get familiar with the product and convince your company to get it at work. Your company pays the API prices to get enterprise features.