I'll chase the bear...
Comparable checks are perfectly legal, but they are regarded as an "appraisal". It is up to the appraiser to decide whether to charge for the work, but they should keep the necessary legal record of it because a true "Comp Check" requires value estimates, aka an "Appraisal" by comparing them to your subject property and tweaking to give an opinion of value. Asking for one is not "illegal".
Most brokers and LOs confuse "comp check" with "recent sales data", which makes appraisers want to kill everyone involved as they have a very specific professional definition for "comp check". Since "sales data" is not used for a formulated opinion of value for the subject property itself, that does not require the appraiser to actually complete paperwork and records for an appraisal opinion. They are merely telling you what prices have been placed on recently-sold houses in a certain area. Along with interviewing the customer as to comparing the condition of their property with the rest of the neighborhood, this is more than enough information for a good broker or LO to form their own estimate to work on the loan structure.
Now, if you insist upon stating or requiring a value for your subject property to the Appraiser, or the desire of specific comparables to create that value, that is not legal by any means.
You really shouldn't even mention your subject property address with your request. To be fair to all involved, you should ask an appraiser for recent sales data ranges in the radius of a stated street-corner, aka "5th and Elm". Hopefully, you have an appraiser that will do that or tell you how to do it yourself, and nobody is compromised legally because you do not tie your request to any specific property.
Boiling it down in a shorter way;
When an Appraiser is "comparing" properties, they are guessing at values and must "compare" them to another specific property you are stating. Because they are licensed professionals to do this, it constitutes binding them legally to those opinions and they must keep a legal record of it, because they could be sued for malpractice if they don't do it correctly. That is an "appraisal" and they need to be paid for their service, like any other service provider. It's like telling a doctor to open you up, set your broken bone, put a cast on you, and THEN tell you how badly it was broken... FOR FREE. If the leg doesn't heal properly, you could sue them for not checking correctly in the first place, because they are legally bound to do so.
When an Appraiser is giving you "sales data", they are just telling you the value of prices that are already determined because the houses were sold for those prices. This does not require them to give any opinion at all and just state information that is already public knowledge. It can be done very quickly and they usually will not charge for this unless you are acting inappropriately towards them.