The proxy exists because there's no way to get programmatic API access to Claude on a Pro ($20/mo) or Max ($200/mo) subscription.
This isn't an oversight. Anthropic has actively taken steps to prevent subscription-based API access. They've shut down third-party bridges, tightened terms of service, and made it clear this is corporate policy, not neglect, not a missing feature, but a deliberate business decision.
Meanwhile, OpenAI opened API access to ChatGPT Pro/Plus subscribers. The result is predictable.
A CTO friend is prototyping an electronic warfare detection system. His existing customers include a major European MNO that operates across dozens of countries. He's currently splitting ~$80/month across four AI subscriptions, constantly rationing tokens, juggling providers. He'd switch to Claude Max tomorrow if it included IDE API access. Instead, he's moving his entire prototype to Codex/OpenAI, because they made it possible.
Here's why this matters beyond one developer: The prototype becomes the demo. The demo becomes the procurement spec. The spec becomes a multi-year enterprise contract. This particular MNO signs seven-figure deals per country rollout. Once the prototype is built on OpenAI, Claude never enters the conversation. Anthropic doesn't just lose one deal, they lose an entire multi-country enterprise pipeline they'll never even know existed.
This isn't an isolated case. In my circle, senior engineers, CTOs, infrastructure people, nearly everyone would switch from Pro to Max if it meant using Claude in their IDE the way they can now use OpenAI. That's going from $20/month to $200/month per user, zero acquisition cost. Even if only 10-20% of the broader Pro base converts, the revenue math is overwhelming.
The proxy ecosystem (claude-max-api-proxy, Antigravity, and others) is direct proof of unmet demand. Developers are writing code to work around a billing boundary. That's not abuse, that's a market signal Anthropic is choosing to ignore.
Claude Opus is technically superior to Codex for most development tasks. That means nothing when developers can't access it in their workflow.
Anthropic built the best model and then made a policy decision to keep it out of the environment where long-term platform adoption is decided.