Being able to work from anywhere is one of the real freedoms of running a small business, and free Wi-Fi in cafes, hotels, airports and waiting rooms is what makes it possible. It is genuinely useful, and for ordinary browsing there is usually nothing to worry about. But it is worth being clear about what an open, shared network actually is: a space you do not control, run by someone you do not know, shared with other people you cannot see. That does not make it dangerous by default, but it does mean it deserves the same instinct you would apply to any public place - fine for most things, not the place to leave your valuables lying open.
The specific concern is that on some networks it is possible for others to observe or interfere with traffic that is not properly protected, and that a network which looks like the venue's official Wi-Fi is not always what it claims to be. Someone can set up a hotspot with a plausible name - the cafe's name, or "Free Airport Wi-Fi" - and hope people connect to it without checking. Once connected, the exposure is only to whatever you send unprotected, which these days is less than it used to be, but "less" is not "none", and the accounts a business cares about are exactly the ones worth protecting from even a small risk.
There are two straightforward ways to remove most of the concern, and they are easy enough to make into habits. The first is to avoid doing the genuinely sensitive things - logging into online banking, handling payments, reaching anything holding customer data - over a public network you are unsure of, and to save those for a connection you trust. The second, and more convenient, is to bring your own trusted connection: using your phone's personal hotspot for important work, or using a reputable VPN, which wraps your traffic in encryption so that even on a shared network it cannot be read by others around you. Either approach turns "I have to be careful here" into "it does not matter what network this is".
A couple of small settings make the habit easier to keep. It is worth checking that a device does not automatically connect to any open network it recognises by name, since that is how people end up on a look-alike hotspot without deciding to; turning off automatic joining of open networks puts the choice back in your hands. And confirming the exact network name with the venue before connecting takes a moment and defeats the simplest look-alike trick. None of this means avoiding public Wi-Fi - it is far too useful for that. It means treating it for what it is: a convenient public room, perfectly good for most work, and worth a trusted connection for the handful of things that really matter.