I'm not sure it is that interesting, it makes sense. Twitter is a huge organization optimized for reach and earning money by serving its audience ads, with big

I'm not sure it is that interesting, it makes sense. Twitter is a huge organization optimized for reach and earning money by serving its audience ads, with big structure around all of that. While Fosstodon is a more of loose collective of people spending their free time trying to run a free service for a community around FOSS, with optimizations geared towards making the service itself cheap to run but still resilient and performant. That they end up at different costs per user at that scale (or even more) makes a lot of sense in my head.