When they capture prices, they're not really capturing trades per se - that's why they call it "price capture", not "trade capture" at the exchange.
They're capturing the latest price a transaction went out on but they're not going to catch each one. They'll miss loads of them and they often won't even bother posting multiples if the price hasn't changed (i.e., you're likely to see only 1040.50 cross when in reality 5 pairs of traders in the pit each transacted at that price at that moment). They also do NOT capture trade volume.
So bar data will generally be accurate, but raw tick data will miss a lot and there'll be no reliable intraday volume at all. So it's probably not wise to try to use tickbars or any fancy analytics that rely on a reliable tick stream.