The Z codes (ICD to be specific) are similar. Although those two are not exhaustive -- it can be conditional so can be confusing.

You have different rules for chronic conditions, so for example something could be rolled up into a billable DRG one visit, but should not be included in a follow up visit.

The DRG example on this website is interesting -- so I think these are valuable services, but I look at claims data everyday for my job and I would have a hard time knowing the exact codes before I go for a visit. (Also obviously in an emergency I am not shopping around!)

And then there are service modifiers for "how long" for CPT codes for just outpatient visits -- you wouldn't be able to know 15/30/60 minutes before hand even if you did know the specific CPT code. So for that you may want to know the proportion the doctor bills, not compare the prices on the same CPT.