Even people with masters degrees can lack awareness of risks in any manner of things, it's not meant as anything offensive, we all need a reminder from time to time on various things!
You said it was a cheap charger hence the comments about safety, I can see a brand logo on that image looking at it closer, Inateck? They seem to be a decent third party who make various USB and power related stuff like Anker/Choetech. It's just when you hear people mention cheap charger, the worst is assumed because that is typically exactly what it is.
Unless a tweet/message to Inateck gets a response, you probably won't be finding the exact same sliding track on another plug that isn't by the same maker.
Yea sorry, I should have been clearer. When I said cheap I meant not £69 from Apple for the plug and an additional £19 for the cable.
Inateck said they were out of stock of the product that I purchased, when I asked about just a replacement plug they were struggling to understand what I meant. They issued a refund and didn't really want to help any further.