loanwords - Pronunciation of W

I often see the alphabet W being transcribed or pronounced as "ダブル" rather than "ダブリュー" in Japanese, and I think that in most cases, that was not what was meant. Indeed, there seems to be a practice of abbreviating "ダブリュー" as W, most often seen in a menu in a fast food restaurant, (whose meaning intentionally or unintentionally goes along with the origin of W being "double 'U' "), but even out of that context, I observe it being transcribed/pronounced as "ダブル", and I don't know if people are doing it because of the origin of the alphabet character W. Why do you think that happens?

Answer

I don't believe a definitive answer to your question is possible. That said, you asked what people think, so a couple of my own thoughts:

When reading out URLs (arguably now the most common use of W in modern Japanese), ダブリューダブリューダブリュードット would be a real mouthful, so it's often pronounced ダブルダブルダブルドット or even ダブダブダブドット. It's possible that this has contributed to the abbreviated pronunciation.

I don't know if you'll agree with this, but I find that the transliteration of borrow-words is very prone to change and evolution over time for convenience or what have you. The meaning "double" on fast food menus etc is probably the second most common use of W in modern Japanese. Presuming this use came first, this could also have influenced a change in the general pronunciation.

Alternatively, as you say, the English pronunciation of W comes from double-U, so you could say the most "correct" transliteration would be not ダブリュー but ダブル・ユー. ダブル would be a sane abbreviation of this, just like many 和製英語 are informally abbreviated, purely for the sake of brevity.