Then you must not have read the linked article, which mentions three companies that have done just that.

Roaming charges made an unwelcome reappearance for UK mobile users heading to mainland Europe after Brexit. EE, Three and Vodafone were all quick to reintroduce the daily or monthly charges to use their mobiles while in the EU – which typically add £2 a day.

Only if they only spoke one language. Googling indicates there are somewhere around 1.45 to 2 billion total English speakers, so just knowing English might hit 25% already.

Edit: Also, the graph only lists languages with 50 million speakers, so the real proportions are smaller.