[TheGorramBatman]

JPEG2000 used Arithmetic coding. But, you'd have to re-write the standard and evaluate it to get JPEG to use Arithmetic coding (e.g. does the way JPEG coefficients are read out still make sense with Arithmetic coding)? There are also other algorithms for universal source coding that exist -- theres nothing to say that arithmetic coding is a good choice, esp. given its relatively complex compared to say Asymmetric Numeral Systems (Duda; arXiv:1311.2540 [cs.IT], though I don't remember where it was published) or (Recursive) Interleaved Entropy Coding (Klimesh and Kiely; NASA/JPL IPN Progress Report 42-146).

Arithmetic coding is just the one everyone knows since its taught in information theory 101 (e.g. Cover and Thomas).