Yes, their wisdom can only be accessed by 500 million Spanish speakers, including around 50 million in the USA.

It isn't just the USA: India has mass transit construction cost problems and could learn - if only they shared a language. Not to mention France (France is better at controlling costs than the US, but still not cheap)

In the US Spanish speakers tend to be poor and thus not in position to do anything about costs if they did look into it.

I'm sure Indians who wanted to go over to Barcelona to learn about the transit system would have difficulty finding a common language, or paying for a couple of translators.

I assume you are making a sly joke, because even if the USA didn't have plenty of Spanish speakers, Barcelona has plentyof English speakers.

I wouldn't expect the people in their transit department are hired for their English ability. Since Spanish and Catalan are important languages there I would expect that I need to learn at least one of them to learn from there. Of course if Spain wanted to teach the world how they do it English would make more sense as it is the dominate trade language today - but I can't think of any reason why Spain would care to teach others. It thus is on the rest of the world to learn Spanish to learn from them.

We might be able to learn from the Chinese or Russians. I'm not sure what their cost structures are like. Learning best practices from high cost areas won't help you control costs, which rules out all English speaking countries.