The Federal Trade Commission on Thursday said it is suing Amazon over the way the retail giant lets kids use real money to buy “coins,” “acorns” and other digital goods on devices like the Kindle Fire. The lawsuit, filed in Seattle, comes after Amazon defiantly stated that it would take its chances in federal court rather than agree to a settlement, which would likely have involved a multi-million dollar penalty and a 20-year consent decree. According to the FTC, Amazon employees stated in internal emails that unexpected kids’ purchases were “clearly causing problems for a large percentage of our customers” and that the situation was a “near house on fire.” The agency also alleges that one mother claims her daughter racked up $358 in unauthorized charges, and that children too young to read had bought goods by “randomly pushing buttons.”