Firstly, given that LO stock is maximised for capacity with a high proportion standing that is a flawed comparision.
Agreed. However, it illustrates how bad TPE overcrowding is that on average it's easier to find an empty seat on a LO train than on a TPE train.
Thirdly, the limited number of seats on LO trains are, even in the off-peak, virtually always all occupied so I would love to see any evidence for this assertion...
Passenger Focus, Transport Focus or whatever they call themselves these days made the claim TPE have the highest seat occupancy level of any TOC (including non-DfT franchised ones) when responding to the TPE franchise consultation. There have been some changes in rolling stock since (6 x 156s replacing 5 x 170s.) Considering that's coming from an Independent Body representing passengers of all operators I don't think there's any incentive for them to provide misleading information. If they did then it may affect any argument for getting more LO carriages.
Do London Overground trains (including the 172s) usually have all seats occupied from start to end or do they fill up and empty out again, also is there a peak flow?
EDIT: Just found a YouTube video someone did of a 14:32 departure from Barking to Gospel Oak. I thought it was wrongly labelled as it looked like an ECS but then I saw a few passengers on it, so obviously very few passengers on services between their first two stations and a low seat occupancy level.