Or don't you have small local businesses (restaurants, pubs, stores) with duplicate names as long as they're in different locations? I know here in Flanders we have, for example, tens if not more places called "Café Onder den toren" (roughly translated as "Pub beneath the tower"). Do all local businesses in the UK have different names?
For example, there used to be a Scottish company constructing steam locomotives which traded under the "Barclays & Co" name - because it was founded by one Andrew Barclay. There's also the Barclay Academy secondary school, and a Bentley dealer which until recently operated as Jack Barclay Ltd.
And that's just the UK ones! Barclays operates internationally, which means they want "barclays.com", so suddenly there's also Barclay-the-record-label, Barclay-the-cigarette-brand, Barclay-the-liquor-brand, Barclay College, golf tournament The Barclays, Barclays Center (whose naming rights were bought by the bank, but they of course want their own completely distinct website), Barclay Theatre, three Barclay Hotels.
Of course there's also all the stuff under "Barkley", "Barkly", "Berkley", and probably a dozen other variations just waiting to be used to scam dyslexic Barclays custumers.
You bring up good points, but I don't think that company naming has to be 100% proof against confusion, it's just one more helpful thing for consumers to identify whom they are doing business with.
In the case of close names like "Barkley", if they're doing banking, there is probably a trademark case against if they actually use it to confuse customers.
Intrestingly enough, "Barkley Holdings" was registered by competing bank HSBC: https://find-and-update.company-information.service.gov.uk/c...
In the US though, every state has it's own registry, and names overlap without the power of trademark protection applying to markets your company is not in.