The only explanation is she was tending to her shrub!
Also, "45 years after the collapse" suggests Max too was born after the collapse, which means MM1 was post-collapse. There was some evidence of social decay but they still had hospitals, ambulances etc.
I guess you have to pick and choose...
It's treacherous to get back into talk of timelines, but if we can figure out how long between Furiosa returning to the Citadel and the events of FR, we'll be a long way towards figuring out the chronology. Given Furiosa starts 45 years after the collapse and covers 15+ years itself.