They don't. What you're seeing is a $50 difference on a $26,000 asset.

($50 / $26,000) x 100 = 0.19%

Bots will always arbitrage any relevant price difference, and the difference in price per platform is mostly related to transaction costs.

Significant price differences are something you see on low volume p2p DEXs, where a $2500 BTC buy is considered large.