You act like they just ask for a random dollar amount with no further elaboration. They show their work in great detail, and if something they ask for is tremendously out of step with reality, they'll of course be questioned about it. Regardless, by the time you as a layperson start seeing plan-based artwork or (especially) a model, everything shown is part of the proposal and has ostensibly been accounted for in the approved budget.
I feel like you've raised this exact topic before, but I guess the answer needs repeating. EPCOT's 40th is one of the rare instances of genuine budget cuts after project initiation, resulting from their response to COVID. While Ratatouille, Space 220, Cosmic Rewind, Journey of Water, and CommuniCore East escaped largely unscathed from the original budget plans, everything else was cancelled, delayed indefinitely, or hastily reworked to cost much less (PLAY!, Poppins, Celebration Gardens, Spaceship Earth, Festival Center, etc.). In this case, it had nothing to do with them cutting scope due to running out of the funds that were originally requested; previously allocated funds were pulled back.