When I learned English, I learned that "luggage" an uncountable noun, meaning the collection of all your bags and suitcases (and/or their contents). From https://en.wiktionary.org/wiki/luggage :
luggage (usually uncountable, plural luggages)
- (uncountable) The bags and other containers that hold a traveller's belongings.
- (uncountable) The contents of such containers.
- (countable, nonstandard or obsolete) A specific bag or container holding a traveller's belongings.
Recently I have been noticing it being used more and more for a single large bag used for travel, what I would call "a piece of luggage", or "a bag". First I heard it used this way by my former roommate, who is not a native speaker, but more recently, I have heard it from my girlfriend, who is a native speaker, and I have seen/heard it used this way more and more. To be fair, I learned mostly British English, and I heard it used in this other way in the United States, so maybe it is a regional difference?
Here is an example: https://www.amazon.com/AmazonBasics-Hardside-Spinner-Luggage-20-Inch/dp/B071NJ24R9/ :
Hardside spinner luggage for work travel, weekend getaways, or as international carry-on
The change I'm wondering about might not be about countability, but rather about some related property. Here is source which is not an amazon listing: https://www.nytimes.com/wirecutter/reviews/best-carry-on-luggage/ where they say for example:
(as long as you register the luggage within 120 days of purchase, which is easy to do on any smartphone)
Here is a Google Ngram for "a luggage" vs. "piece of luggage", I realize that "a luggage" also finds "a luggage cart", etc. but there is an increased use of it since 1980, and a sharp decline in the use of "piece of luggage" since 2012. https://books.google.com/ngrams/graph?content=a+luggage%2Cpiece+of+luggage&year_start=1800&year_end=2019&corpus=26&smoothing=3
Is this a change that is happening, and what is causing it? Or have I just been wrongly pedantic about the word (I have never corrected anyone, but using "luggage" as a countable noun does sound wrong to me)?