It kind of explains why weddings in Israel are so expensive, I heard it's almost cheaper to buy flight tickets to buy wedding dress in another country.
Not only, it is normal also in Poland (though it is normal that people give both physical gift and cash).
Traditionally, people often registered somewhere like a department store or a kitchen goods store. Some of the function of gifts was historically to get a young couple moving out of their parents' houses a start. Of course, these days a lot of people are pretty well set-up before they get married.
That's tricky though. Often enough, people really don't know or think enough to match properly, which causes the gift to end up being offloaded somewhere else later, and/or breeds silent resentment.
It's not just when people don't know what the recipient is interested in, but importantly, when they think they know, but don't understand that you shouldn't buy something related to someone's interest/hobby if you yourself aren't comparably proficient in it.
> Cash is not specifically matched to its recipient.
In some sense, it's maximally matched to every recipient, by virtue of being universal. Question is, is the gift supposed to be about recipient, or about the gift-giver? Super specific gifts are often about the latter.
(The exception is if there's some other social expectation that specifically says that the gift should be cash, like Jewish wedding gifts).