Good find, but a scan of the map leads me to think that this refers to the I-190 spur between 90 and Grand Island. I guess it was tolled back then? I don't remember. The "free Thruway" gap on 90 must predate this, but unfortunately online reading material on this road-building history is really limited.
The "promise broken" thing doesn't bother me, maybe because I wasn't around back then. But in hindsight it just looks like an honest mistake, a policy lesson. America had never attempted anything on the scale of interstate highways at the time when the Thruway was built, I'm sure the intentions were good but the state was so far off in thinking that it could afford perpetual maintenance. Society's come a long way, for better or worse, since the days of unlimited free money for highways, we've learned a lot. We haven't raised the federal gas tax since the first Bush administration and it'd be irresponsible, in my opinion, not to have some user fees on the Thruway to keep it in decent repair.