This is particularly noticeable in Europe. Due to the European Union's thinning/erasure of borders, there is an order of magnitude more inter-European travel and mobility than 10 years ago. And the most widely understood language between these travelers is English. In Barcelona, vendors would speak to Dutch and Chinese tourists in English. Even in Paris, famous for its disdain of English, the language is fairly widely spoken, not so much to accommodate the British, but visitors from the rest of Europe and the world.
Folks quickly figured out that instead of learning multiple European languages (and even then, only be able to communicate with other Europeans and people from former European colonies), they could instead learn English and be able to communicate with not only Europeans but people from Asia, the Middle East, etc.
English is used even among people of the same ethnicity. I was with a friend at a restaurant in Chicago's Chinatown, and noticed that my Cantonese-speaking friend had a hard time conveying her order to the Mandarin-speaking mainland Chinese waiter, so they both switched to English. The communication was successful.
Practical, but we already got one, that is English. Even this post itself is written in English to reach bigger audience.
And I would argue Esperanto is hardly universal for the world, more for european languages.