Cashless is a multi-part win for the wannabe ruling class. You covered the surveillance angle which is the biggie, and obviously there is the interest on credit cards (sometimes very predatory interest).
The less obvious part is the huge amount of profit the banks take in acting as middlemen, and how they can and will collaborate to increase their piece of the pie of almost every transaction. Right now paying with a credit card in the US results in them taking about 3% of the whole thing. Cash can still compete, and some stores and other vendors offer cash/check discount pricing. But if the war on cash is successful, there will be less customers with cash and with less customers dealing with it, it will be less useful to deal in cash for vendors. With credit cards holding a monopoly position, in a perfect market the different card companies would compete and we might see less of a middleman's take. But banks are banks, and we know what they like to do. Expect their take to rise. Of course the expense of their cut gets passed on to buyers in the form of higher prices.