Any .m4a file you see which has a higher bit rate than 320 kbps is Apple Lossless which is equivalent to FLAC, Shorten, etc.

In today's world with much larger hard disk drives, faster connections, there's really no reason why people don't share more lossless files other than through lack of education/ignorance & marketing. There's still the stupid ones who went with the early propaganda of mp3 & think mp3 128kbps is equivalent to CD quality. lol And then there's those who don't care, etc. as suggested by Sleepless.