>>— the setting depicted looks like a commuter rail setup where I would imagine it's fairly lengthy runs of powered vs unpowered.

It says in the article - only 20-30% of the route needs to be electrified for these to work. And the batteries can be recharged at stations in 20 minutes.

"It shows that Siemens Mobility’s battery bi-mode trains would only require 20 – 30% of a line to be electrified. These trains, utilising Lithium Titanate Oxide battery chemistry, can charge their batteries to full capacity in 20 minutes whilst moving along the electrified sections or charging whilst stopped at stations."