There's a number of reasons why somebody can't or is unable to opt-in via financial payment. And tolls often become egregious taxes on the poor.

It wasn't long ago a fire department in Tennessee let a house burn because the owners unknowingly hadn't paid the $75 fire service fee. 

 This was unfortunate but something easily fixed by stopping the “unknowingly hadn’t paid”. First line of defense for this is to have an auto-pay set up, like is a good idea for all bills. If that doesn’t work for a particular household, the fire department is incentivized to send a letter/advertisement to their house informing them and selling them on paying for the service, so they can make more money and (in case of fire) protect the house. There are (very) occasional problems for a few individuals, but it’s still more moral than stealing money from the entire population, including those that have adequate homeowner’s insurance, which this guy noted that he didn’t. 

 This was unfortunate but something easily fixed by stopping the “unknowingly hadn’t paid”. First line of defense for this is to have an auto-pay set up, like is a good idea for all bills. If that doesn’t work for a particular household, the fire department is incentivized to send a letter/advertisement to their house informing them and selling them on paying for the service, so they can make more money and (in case of fire) protect the house. There are (very) occasional problems for a few individuals, but it’s still more moral than stealing money from the entire population, including those that have adequate homeowner’s insurance, which this guy noted that he didn’t.