But still, somehow, there is a subset of commentators in this thread that aren't aware that it only takes ONE dishonest person to jack your shit.
In a coffee shop with 20 people that is 5% of the population. Almost 3% of this country's population is under correctional supervision at any given time. The odds are not in your favor. Carry a backpack for your stuff and take it with you to the bathroom. If you lose your seat it is a small price to pay for something that doesn't belong to you anyway.