They have their own opinion on what a "comparable vehicle" is.
Funny thing is many policies allow for the insurance co. to also purchase a replacement vehicle for you. Almost no one takes it up, and I've seen it happen only once, and they paid more for the replacement than they offered initially.
Going 3rd party is usually a take-it-or-leave-it scenario. If you have collision, you can at least invoke the appraisal clause.
Ins adjuster doesn't care about condition or or pictures etc, they mark everything as average.