Earlier quoted context omitted.
> This is just a convenient data grab and profiteering. I know people working on this project, and that is absolutely not their motivation. They want to better understand the movement of people within the system, so they can design better stations, trains, and services. The traditional way of understanding such passenger movements is by parking students with clipboards and people-counters all around stations, doing p…
The point that this will be only used to improve services was denied in the article itself: "What they told people at the time was we're going to use this data to improve services. But now thanks to [Sky News] investigative reporting, we find out that it's partly to improve the services, but also it's to exploit people's data for revenue, doing advertising."
But that's literally all they're getting from this: spatially granular and accurate passenger movements. They're not collecting personally identifiable data or even aggregated demographic metadata. Just footfall counts. (Read their policies: they just collect device MAC data, which is hashed with a salt that is destroyed on a daily basis. This allows them to trace MAC addresses through the network without ever being able to trace it to an individual.) But, yes, those footfall counts are relevant to advertisers. So? TFL isn't a profit-making organisation: everything they get from advertising is re-invested in operations and new infrastructure.
Anyhow, you're trusting them with your life when you ride they're vehicles. They do a pretty good job with that. Trusting them with fleeting awareness of your MAC address seems like a much smaller ask.