Common misconception due to movie brain. The average "salary" of a misc gang member is under <30k per year. Violence is cheap any male under 30yo can easily do it and the poor ones are often willing. Junkies will often do anything including murder for next to nothing ie another hit. Junkies are actually quite reliable contrary to movie brain beliefs.
Anyway wrench hitting does not need to scale. They only want the passwords of people they perceive as being a threat to them which is a very small number of people.
Firstly, ICE agents are making six figures. So in this context it is. You pay for loyalty and secrecy, that is how the government works and how the mafia works.
Secondly, it must scale. If the list of perceived enemies is great, you must have great scale to execute violence. If it is small, you must have great scale to execute surveillance. If your surveillance is violent, such as shaking people down for their computers and passwords, then you need scale to attack both large and small enemies.
This is why mass surveillance (and prevention thereof) is a meaningful hurdle. The alternatives are physically challenging.
The application of the XKCD comic is misleading. It is like saying, why lock your doors at night when a burglar can just bust down your door or pick your lock or break in through a window. The purpose of a locked door or encrypted computer or any form defense is to force your enemy to engage in more expensive and limited measures in attacking you.
