Georgina. Thanks. Interesting. But consider;
1. If we have >2 identical detectors or eyes at rest side by side in an ambient medium they find the SAME from ALL signals. If one is different, rotated, moved or in any relative motion, THEN, we agree, finding always differ. To me the evidence is clear, 'observer dependence', but does it also agree with the signal having NO measurables pre-interaction!? (does it help to think 'wavefront' not requantized 'particle' PRE interaction).
2. You say; "I was not saying that the velocity of an observer can somehow affect the frequency of light that is distant from it." Sorry I wasn't inferring YOU did, I was identifying it's SR that must infer that - as it ignores 1 above. But we're used to describing 'frequency' when it's crucial to remember wavelength lambda is the scalar measurable. On lens interaction we can't compute any 'frequency' until we sent the revised signal (& lambda) up our optic nerve/cable to our processor to calculate against time! Can 'frequency' then be a more fundamental property? Astrophysics only makes any sense by using lambda.
3. : "Motion involves questions of position and location (same thing) and distance." I see your quest for simplicity, but all 'motion' really needs is some "relative velocity" of anything i.e. WITH some ambient medium or other body. If none exists then consider; NOTHING exists! Is it not worth considering that really ALL 'energy' is kinetic, i.e. motion based. Kinetic just means linear as opposed to rotational. What else is there? Even 'potential' energy only comes to exist once motion starts.
4.; "I think that the Bell's inequalities argument doesn't apply as it is based on the assumption that things are happening in space-time". Absolutely NOT! QM can't use space-time. One of the main chasms with Relativity is QM's simple 'absolute' time! Yes, I agree something has to give, but 1. above shows it's NOT 'measurables'. NASA & the ISS couldn't communicate with probes if it were! A simpler answer is known to science; wavefronts (& 'particles') have freedom on all 3 (x,y,z,) axis and use it; (thus elliptical polarity etc.) So states vary in all cases except 'side by side', as found. Does that make sense to you?
So just a couple of key queries. But of course scoring is not about agreement or veracity so no points lost by theory!
Very Best
Peter