https://www.nelsonmandela.org/omalley/index.php/site/q/03lv0...
You're right that you need to have people on the streets or in office to get anything changed. I think too many people forget this and forgo the slow hard work of street-by-street politics and downticket races.
But I think the fight about making cryptography available, really is the fight for right to privacy, and even right to secrecy in certain areas of our society. The USA is fortunate in some ways because of the constitution, and its repercussions throughout modern history - even if law enforcement can build or buy a device to see through walls, that doesn't allow such tools to be used without regulation.
But now is the time to regulate large scale meta-data, traffic analysis, in addition to guaranteeing a right to technology that allows data to be kept secret.
Sure, you still need to buy things in person, which can be done with cash. But drug dealers seem to be able to do a pretty good job of evading taxes.
Imagine if everything that you bought in person was done with cash, or a bitcoin payment. That money would be untaxable.
If you buy a house, for sure, the government can track that, and you need to make sure the money used to buy that is "clean", but a surprising large percentage of a person expenses could be done in a safe way.
Buying a house or renting housing leaves a paper trail. So does renting or buying a car from most places that sell or rent cars. So does paying utility bills. So does paying for prescription drugs, medical services, car insurance, life insurance... So does paying for higher education.
I guess if you had some cash-only tax evading side business you could use cash to buy things like food, clothing, gasoline, and miscellaneous household goods. But you're not going to be able to dodge the taxes on middle class life's major expenses -- at least not without tripping the same mechanisms that catch drug dealers buying cars etc. with cash. I suppose you could live like an off-the-grid survivalist who never interacts with ordinary businesses. That looks like a lot more work than living an ordinary life where you work at jobs that don't involve trusting other criminals, buy things and pay taxes like usual.
You're also assuming that the government would sit still in the face of a serious erosion of the tax base, and not crack down on it. The US is bad enough with its arbitary seizures of cash, let's not destabilise the situation further.
Just because cryptography isn't useful for that particular case doesn't make it not useful for other cases; no one is arguing crypto will fix all government abuses. It doesn't mean it isn't a useful tool, though, in fighting corrupt governments.
In countries like the USA, or even Apartheid South Africa it can have a much bigger role in organizing protests and other activities.
ETA: This quote from May especially struck me “Would Hitler and Himmler have used ‘key recovery’ to determine who the Jews were communicating with so they could all be rounded up and killed?” The Nazi's wouldn't have really cared what Jewish people were saying because they just wanted to kill them. Similarly if we think of something like the Soviet Union while cryptography would have undeniably been helpful for dissidents for coordination and getting ideas out ultimately you still need to have people on the streets or in office to get anything changed.