I believe the official name is "surtitles", as they appear above the stage. (One small advantage for the cheap, high seats with easy view of surtitles.) Those are pretty standard these days in the big theaters. Don't be fooled that the Germans and Italians are understanding all the lyrics. With the long, drawn out notes and flourishes from the orchestra drowning out the singers, many/most of the native listeners are following along because they already know the lyrics. Ditto for the few operas in English. I have had surtitles for Nixon in China, and definitely needed them.
I have never seen an opera not do this. In Turin they offered subtitles in both the original language (English, as it happened) and in Italian, which was cool. I think some of the objections here come from people who really don’t have much experience going to opera. It’s pretty affordable in San Francisco, and it’s a lot of fun; I recommend everyone try it out.
A long time ago I went to an opera with real time subtitles, it worked well. I didn't know that it was uncommon to be subtitled when in a different language than the one spoken in the area.
Very few opera houses offer subtitles. This is because subtitles near or on the stage would be difficult to read due to the heads of those in front of you.
Some (e.g. Vienna) have a seat-back system that shows subtitles.
Surtitles, on the other hand, are pretty much ubiquitous.
If you get to know it first before you see it live, you will enjoy it more, and that won't be a problem. Then if you don't like it, you can save your money and see something you like instead.