As a driver, we all know at our depot that there are 'good', 'bad', 'ok', 'great' and everything in-between driving styles. A lot of this will be based on when they were taught. Similarly, all drivers have 'off' days or runs.
A restrictive (double or single yellow) aspect must allow a minimum service braking distance until the driver encounters the red. That is to say, the driver will always be able to stop should they react positively when they see the first restrictive aspect, with the rare exception of instances such as poor rail adhesion. Route knowledge will then tell you how quickly you need to get the brake on and the speed off factoring where the red is, the speed you're doing and the railhead conditions.
Sometimes, when I'm driving at 100mph, I encounter a single yellow and I know I haven't got much room until the red. The brake is applied firmly to get the speed down; in this instance it's possible someone on their feet may think, that's a bit rough. That's different to a driver who throws the train around. It's easier to drive poorly than it is smoothly. I'm not going to apologise for firm braking if it's warranted, and if I need to use the emergency brake, I will. I have sometimes applied the emergency brake then to release it when whatever I've applied it for is no longer a danger (some trains you can then release without coming to a stand). Yes, this causes the train to handle roughly but better than flattening someone.
We've all encountered poor driving, but sometimes it can be misinterpreted if you're not in the know or upfront.
Reading between the lines on Lumo, their drivers are new to the route, new perhaps to high-speed driving, new to the stock. I would think the Peterborough incident is due to poor route knowledge, which is down to both the training and the driver. But more widely, I would think the raib report will highlight that more needs to be done to train new drivers on the route, given the speeds and associated risks involved. I'm not judging the driver, it happens to us all. You learn the route properly when you're on your own, you just need to stay safe in the meantime.