"Surgical" doesn't necessarily mean invasive. It's most likely a procedure similar to rhinestone implants[0].
As for why they use a 1-way device: this method of cheating has been around for decades; you get someone to take the test, they leave early and radio answers in. I don't know the specifics for this particular exam, but India is certainly not the only place in the world w/ extremely competitive admission exams. Back in my days back home some twenty years ago, cram schools would be on stand-by outside school doors, they'd smuggle the question sheet out somehow and flash-solve them / publish answers on the spot for publicity. You could get a full answer sheet online from a cram school website before the exam was over (these exams are hours long) and test takers would frequently do so after finishing their exams to see how they did.
My understanding is it was an all-hands-on-deck, divide-and-conquer thing. The big brand cram schools had literally hundreds of teachers whose only jobs was preparing students for admission exams. They could easily have each question solved by 5 different teachers in parallel.
If the teachers are so good at these exams that they can flash-solve them, why aren't they doctors? Surely that pays better than teaching at a cram school?
Teachers typically specialize in a single subject and tests are multi-disciplinary. The subjects can range from literature to chemistry to history to physics. As in, you have to be at the top of the pack for literature questions even if you're applying for engineering. And recall, these are no pushover questions; I've taken some of these elite school exams as well as the american SAT/SAT 2 and the SATs are child's play in comparison.
Also, competitiveness for some disciplines is seriously no joke: to give you an idea, medicine at Harvard has an admission rate of around 3.5%. Medicine at University of Sao Paulo, Brazil has an admission rate of 0.8%. Admission rates for IIT, India are even worse, at around 0.59%.
And if that isn't discouraging enough, many of these schools have reputations of being "hard to get in, harder to get out" (meaning that actually graduating is ever harder than getting accepted into the program in the first place)
As for why they use a 1-way device: this method of cheating has been around for decades; you get someone to take the test, they leave early and radio answers in. I don't know the specifics for this particular exam, but India is certainly not the only place in the world w/ extremely competitive admission exams. Back in my days back home some twenty years ago, cram schools would be on stand-by outside school doors, they'd smuggle the question sheet out somehow and flash-solve them / publish answers on the spot for publicity. You could get a full answer sheet online from a cram school website before the exam was over (these exams are hours long) and test takers would frequently do so after finishing their exams to see how they did.
[0] https://www.bodycandy.com/blogs/news/microdermal-implants-bo...