gobble_ghoul

Maybe because in American accents, most of the schwas are R-colo(u)red or literally a syllabic /r/, while in most British accents they are plain schwas or schwa with an /r/ inserted after if the next sound is a vowel as in Panda-r-Express.

From an etymology standpoint, flower=flour.

Respectively, those words would be /kʌlə(r)/, /fleɪvə(r)/, /lɔː(r)/, /vəreɪʃəs/, /haʊs/. Sometimes “voracious” has the same first vowel as “lore”, but usually it gets a schwa. AFAIK “flavour” and “colour” always have schwa in the second syllable. All the words have roughly the same variations in pronunciation in both the UK and US.

I’m not aware of an accent where they would be pronounced the same tbh.