Of course you won’t hear about it. Certainly enough private contractors were “chomping at the bit” to take the people’s tax money to build the system, which suppressed any initiative, never mind suppressed any questions about constitutionality.
I’d be fine paying tolls if it meant not having to pay Uncle Sam any gas tax. At least I would not be wondering what they did with that money, since it all goes into the general fund and gets “transferred on paper” to the so-called “dedicated fund” (per the FHWA themselves).
Private construction firms did the actual building of the Interstate System so I don’t quite get your objection. How is this any different than how other highways have been built?