Why is "slow 4G" the default in Google Page Speed?

[jrbartlettjr]

Please describe the Google assumptions for maintaining the defaults for the Google Page Speed tool at "slow 4G" as per this article: https://github.com/GoogleChrome/lighthouse/blob/main/docs/throttling.md vs mid- to fast-4G given that 5G is at 50% or greater availability and in real-world usage, business users are as likely to be connected to wifi at even higher speeds.