Those machines are located in England. So I would guess Whirlpool have used symbols on the dryer so that they can sell exactly the same machine in any European country without having to make any changes to accommodate the local language.
This is often the case in Europe. Although some machines (Miele for example) do produce a specific machine for each country with writing in the local language. Whereas in the USA everything is usually written in English on the machine. I do notice that the washer does have English writing rather than symbols though. I also notice that they are selling these used machines and are claiming that the washer has had light use for 18 months and the dryer hasn't been used. Hum...I wonder!!!