What you say is true for small purchases of consumer goods. For a multi-million dollar infrastructure, the cost is the same each month. I realize that's counter-intuitive if you've never managed a business.
The provider sets up a deal with Netflix and they see they'll need $100 million of equipment to upgrade the city. They figure th. e equipment will be replaced in five years. They can get that equipment in any of three ways. They can lease the equipment. You may have noticed that businesses lease a lot of stuff - copiers, cars, all kinds of things. You wouldn't lease a home computer, but businesses often lease computers. The reason will soon be apparent. If they lease the equipment, they pay $X per month every month, from the first month to the last. Since the equipment will need to be replaced in five years, they do a five year lease.
Instead of leasing, they can put $100 million on their Visa card and make monthly payments. ;). They borrow $100M from the bank and make monthly payments. They'll need to do it again in five years, so they need to pay this loan off in five years so they can afford the new one. The payment is the same every month.
Lastly, they can use the cash they have in the bank. They know that they'll need to replace the equipment in five years, so they better start saving up so they'll have $100M to do it again in five years. Every month, they put aside some money for the next upgrade. They set aside the same amounteqcheach month.
This isn't pocket change, they don't just get $100M from their wallet. They either borrow and pay back monthly or they save up monthly but either way it's a long term expense paid for over time.
You can see that all of the three options end up like a lease - they pay five years to use stuff for five years. The lease just makes the exact term and cost explicit. That's one reason why businesses lease more than individuals - it clarifies, simplifies what's going to happen anyway, and that clarity is good for the accounting and taxes. (No need to argue with the IRS over the value of five year old SFP modules).
So that's how capital expenses like upgrading a city wide network end up being paid as steady monthly expenses, no matter how the deal is structured.