I've read a few threads about the same question and seem to have really missed something from music theory 101.
My question is around, for example, Cant you See by Marshall Tucker. Very simple progression, D, Cadd9 and G. D starts and ends each verse.
The key of this song is G correct, even thought starting and ending on D?
I my limited understanding, C and D are major and 1 step apart therefore must be the IV V and G must be the I.
Yet, everyone I play with solos this with D minor. Sounds fine, but seems incorrect.
D Mixolydian has all the G major notes, so that makes sense since there is such an emphasis on the D chord, but playing D minor pentatonic has the F instead of F# that is in D Mixolydian.
Am missing something obvious? Or am I correct to say the chords of D, Cadd9 and G are in fact G major in 5,4,1,5 progression and just happens the D mixolydian is probably the best scale choice?