Can a train or a railway line "enter operation"?

Question

I have come across the article Learning from Las Vegas: what the Strip can teach us about urban planning and saw this sentence, "the Las Vegas monorail that entered operation in 2004 has had to defer the dream of connecting the airport, the Strip and downtown."

Entered operation is very new to me. I have asked many native speakers, almost all of whom said it is unnatural or unusual, if not totally wrong (some did say it is wrong though). But I have found many references online, many of which were written by native speakers. So the following are my guesses, correct me if I am wrong.

1. Enter operation is unusual, even considered wrong by many. It might be an old fashioned usage.
2. People who use it might think of go into operation, because go into operation is common, and enter sometimes means going into, that's why they end up with "enter operation".
3. or it might be because people who use it think of "enter service", which is also common.
4. but feel free to say if you think it is perfect English. :)

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I have edited and expanded this question. Do you think it is right to say "The China-Laos railway recently entered operation/service"? A friend of mine said usually a new train enters service, but a railway line or the entire thing does not. Of course, the part of "enter operation" is just similar to my original question. Thank you

Answer 1

This seems fine to me. It corresponds closely to this definition from Merriam-Webster

5a:
to make a beginning in
enter politics

My Apple dictionary has an even closer definition, I don't know an online link.

start or reach (a stage or period of time) in an activity or situation:
the election campaign entered its final phase.

Answer 2

Personally I find nothing unusual about "enters operation" but I wouldn't use in when speaking casually, which is why some people might think it is incorrect without proper context.

The word "operate" appears a lot in the train industry (train operating company, train operator, trains that operate on the X line), so perhaps "enters operation" is often used in the industry. However, I find it very usual to say a railway track itself "enters operation" as it is the trains that operate along the track/line.

A quoted google search for "entered commercial operation" also has over 30,000 results, mainly referring to when energy plants start producing energy for commercial use.