Seems like there are two different issues at play here.
1. Use of generic domains
"Booking.com" was able to be trademarked because it included the domain extension ".com" which made it unique. "Booking" on the other hand can't be trademarked because it's too generic unless it was used for a non-booking related product or service (e.g. restaurant or game).
The three examples you mentioned aren't all the same and we don't have all the information at our disposal to adequately assess the situation. For example, Trivago is a search engine that compares prices on Hotels.com, Booking.com, and others. We also don't know how much exactly each company spent on marketing among other factors. For instance, Hotels.com/Booking.com were founded in the 90s when it was much cheaper to market with much less competition. Trivago was born much later during a time when people hated ads and they had to compete against already established brands which meant they had to spend more marketing dollars to cut through all the noise.
On that note, just think about all the world's top companies (e.g. Google/Alphabet, Amazon, Apple, Microsoft, Facebook, etc). How many of them use a generic keyword-based domain that describes their primary business activity? Every one of them had the opportunity to use one during the early days but didn't because they realized the value of using a brandable name instead. Otherwise, Google would have used something like Search.com, Amazon would have used Books.com, Apple would have used Computer.com, etc.
As an added benefit, using a brandable name also allows companies to expand into other synergistic areas of business more easily without having to re-brand everything. For example, if Apple had used Computer.com back in the day, they would've had to re-brand themselves when the iPhones took off with a
brandable name. And that would've meant losing a chunk of their target audience due to all the confusion created by the re-branding.
2. Use of the name Welry
Now sure this company could've used something better than "Welry" but as we all know finding good domain names that are still available is pretty damn hard! Also, we have no idea what type of data they used to conclude this was a good name for
their company. For all we know, they came up with a few options and A/B tested them in a focus group.
At the end of the day, we have to remember that we're all human and a product of our environment. That makes us naturally biased towards things that each of us personally experienced throughout our lives. We domainers are no different than the person who probably made that decision to use Welry. It was what he/she thought was best for their company. So let's give that person the benefit of the doubt rather than prematurely criticizing the decision.
Contrary to what we domainers think, domains are a small piece of a much broader puzzle of executing a successful business. And 9 out of 10 times, we don't have enough information to assess the situation from the outside. It's easy for us to sit here in our comfy chairs and judge other people's decisions but we have to keep in mind that those people are making decisions based on their own biases and unique set of past experiences. Just like how you and I have come to our own conclusions based on our own past experiences. Let's respect that and the world will be a much better place.
