The patriots stadium construction was owner funded.
"After the Hartford proposal fell through, Robert Kraft paid for 100% of the construction costs, a rare instance of an NFL owner privately financing the construction of a stadium."
That doesn't mean the city paid for it. If you start a new land development to put up houses, you often cover all the costs associated with putting in roads and signs. Not saying that's what happened here but one sentence saying a road was put up doesn't indicate paid for by taxes.
Did you miss the below quote from the linked article?
"...After the Hartford proposal fell through, Robert Kraft paid for 100% of the construction costs, a rare instance of an NFL owner privately financing the construction of a stadium."
Concurrently announced was a new road to access the stadium from U.S. Route 1, and an additional 3,000 parking spaces to accommodate the increased number of fans.. In other words the stadium is only part of the total construction costs. But, politically indirect costs where an easy sell.
"After the Hartford proposal fell through, Robert Kraft paid for 100% of the construction costs, a rare instance of an NFL owner privately financing the construction of a stadium."
[https://en.wikipedia.org/wiki/Gillette_Stadium]