I agree with everything you said except your first sentence. Why should people rightfully expect walking and biking infra to be paid for when it contributes so little to their economy?
And besides it’s really depressing to be so isolated and only get around in a little metal box.
Walking is not merely some sort of hobby. It is transportation, a means of getting from one place to another -- often the most convenient and pleasant means. And transportation infrastructure certainly falls under the purview of local governments.