yeah they had a bit of a problem with this when lyft's original surge pricing was billed as a 'mandatory tip'. But they corrected it by eliminating the word 'tip' from primetime when the started taking a cut from it. There was about a two week period when they were not in compliance with the laws on the matter despite that I emailed them in advance of change warning them this was going to be a problem.
https://help.lyft.com/hc/en-us/articles/213815618-Lyft-Commi...
"Lyft takes no commission from tips, which passengers can add easily through the app. That's right — drivers always keep 100% of tips, whether it's a buck or a Benjamin."