[wc-]

Per FINRA rules: Cash accounts are effectively limited to a settlement schedule (at least a day) in which the unsettled funds from one trade cannot be used for another trade. If the unsettled funds are used for another trade, it begins to count toward pattern day trading. Attempting to bypass the pattern day trading limitation with a cash account can also be subject to good faith violations.

So to follow FINRA's rules, Robinhood will limit cash accounts from pattern day trading as well as margin accounts. The rules applied to margin accounts are stricter, but truly day trading in a cash account won't work for long.