• by Wendy Davis , Staff Writer @wendyndavis, December 9, 2015

Comcast's metered-billing plans have sparked criticism by consumers, advocacy groups and at least one rival online video provider.

But CEO Brian Roberts insists that the company's controversial billing system is in line with practices in other industries. "If you drive 100,000 miles or 1,000 miles you buy more gasoline... If you turn on the air conditioning at 60 versus 72 you consume more electricity,” Comcast CEO Brian Roberts said at Business Insider’s Ignition conference this week. He adds that the same system holds true for data usage and for wireless devices: "The more bits you use, the more you pay.”

Many Comcast subscribers still have unlimited data, but the company has been rolling out usage-based billing in test markets across the country. Customers in those areas -- around 15% of Comcast's broadband footprint -- can only consume 300 GB of data a month before they are charged overages of $10 per 50 GB. The company also is experimenting with charging subscribers an extra $30-$35 fee for completely unlimited data.

Currently, around 8% of people in affected markets consume more than 300 GB and must pay overages, according to a company spokesperson.

Critics say the caps are entirely arbitrary. They also say that cable providers like Comcast have an incentive to price broadband at rates that will discourage people from replacing their cable video packages with streaming services. Public Knowledge, which has been pressing the Federal Communications Commission to investigate data caps, has said that people who want to replace cable video with streaming offerings in HD will need at least 684 GB of data per month.

Observers also point out that cable companies like Comcast can bill people in ways that discourage them from using rival services. For instance, Comcast unveiled "Stream," a $15-a-month streaming television service that won't count against users' data allotments.

So far, Roberts' defense of Comcast's usage-based billing hasn't impressed company's critics.

Matt Wood, policy director at the advocacy group Free Press, points out some flaws in the CEO's reasoning. "It's not actually a consumable resource," Wood tells MediaPost, referring to Comcast's network. He adds that the network is more like "a pipe" than electricity or gasoline. "It's either being used or not, but the capacity doesn't go up and down," he says.

Wood adds that Comcast's billing scheme is comparable to charging TV viewers based on the number of hours they watch television, instead of the number of channels they receive.

Karl Bode at DSLReports notes, also notes that broadband isn't comparable to gas or electricity. "Whether Comcast's delivering 10 Mbps or 100 Mbps, the cost to do so remains fixed. While there certainly are network capacity issues at play (usually overcome with modest infrastructure improvements), the comparison to real utilities ends there," he writes.

"Comcast is simply creating artificial shortages here where none exist," adds Brad Reed at news site BGR.com. "The costs associated with moving data from one point to another are nothing like the costs of producing electricity or water. This is why ISPs have been able to offer unlimited data usage for so long without going broke."