A study being delivered to Congress says billions of dollars in taxable income may be going unreported each year because the IRS has been so slow to adapt to the peer-to-peer economy, Bloomberg reported. More than 2.5 million Americans earned income via on-demand platforms like Airbnb Inc., Etsy Inc. and Lyft Inc. in 2014, and the companies generated an estimated $15 billion in revenue, according to the report. But the companies don’t withhold taxes on the income they pay to people who provide services or sell items via their platforms.