Originally Posted by
Gulliver_UK
I assume one of the reasons is that the DLR was designed to operate on a much lower staffing basis than the Underground. Every time you have an operational gate-line you need an attendent, whereas with the readers revenue is protected by random ticket inspections (at a lower level of overall staffing).
Indeed. However, there is nothing to stop the Oyster readers on the DLR being placed in exactly the same sort of positions across the station entrances as the Underground does, just without physical gates, apart from parsimony with the installation budget, and a "not invented here" attitude of being different for difference's sake.
It works exactly like this at suburban Underground stations when there are no staff present, when for safety the gates all have to be kept open but the readers still work.