I don't know why these sort of things don't work on a reimbursement basis. Instead of just handing over a huge chunk of money, why shouldn't telecoms be required to submit invoices for reimbursement on qualifying work? It would ensure taxpayers were only paying for work actually completed, not empty promises.
At this point, it would be more efficient to just give the money to municipalities directly and just tell them to build their own infrastructure.
Government incentives for commercial companies aren't always bad, but in this case I think they're really clearly not working, and we're just shoveling more money into that hole.