Pressing vs Card Doctoring?
 

Why do comic book collectors accept pressing and other restoration techniques and us card collectors frown on it?

Would it be accepted in the card world if grading companies distinguished it as an altered card as they do in comics?

What's the tell in comic book pressing, how do they know? Graders really can't tell when a card has been smoothed out, unless it's been done so forcefully the card stock is smashed thin.

Baseball cards have always been different than most other paper collectibles related to restoration. I can't tell you how it all started, but that's the current situation.

As far as cards vs comics with relation to pressing, I think it has to do with the thickness of the paper involved. With baseball cards the graders have usually been able to tell when a baseball card corner has been pressed down. With something as thin as a comic, I doubt it would be easy to detect.

I thought it was interesting what they say on the CGC website regarding pressing for comics:

"CGC does not consider pressing to be restoration. Read more on the CGC website. CGC also does not consider dry cleaning to be restoration, which we automatically include in our pressing service when necessary. Dry cleaning’s main purpose is to remove soiling or unwanted substance or writing from a cover, particularly in the white areas. Dry cleaning does not remove tanning, stains, pen or marker, sun shadows or foxing. If we feel your book’s grade would benefit from a dry cleaning, we will automatically perform this during the press process."

Cleaning and pressing comics does not result in an altered grade though. Because they're not alterations lol

If PSA was smart, they would offer in house doctoring I mean restoration services themselves. Vertical integration. Imagine the website: X has three decades of experience doctoring cards, and has doctored some of the most famous cards in history. His expertise ranges from Old Judges to T206s to Goudeys to Topps. PSA is pleased to offer his services to our customers at a reasonable charge.

They have it on the coin side...https://www.pcgs.com/restoration as does NGC
https://www.ngccoin.com/ncs-conservation/

I have posted this before. It's Talmudic.

PCGS Restoration Dos and Don'ts
Submitting a coin for PCGS Restoration in no way guarantees the upgrade of your coin. If the coin is already in a PCGS holder, it is guaranteed not to downgrade, nothing more. Through our restoration service, PCGS is committed to preserving and restoring coins to their original and natural condition.

Toning
PCGS Restoration will not remove original toning simply to make a coin white.
PCGS Restoration will never add toning to a coin.
In cases where PCGS determines that removing toning is necessary and desirable and will not detract from the coin, it may be done. This type of toning may be the result of improper storage, interaction with corrosive materials, or a stain due to an accidental spill.
Surface Contaminants
PCGS Restoration will remove any contaminants that are determined to have been deliberately and artificially applied. Examples include putty, dumdum, grease and other substances known to be used by “coin doctors.”
Restoration will remove contaminants introduced to the coin's surface through improper care or storage. Examples include PVC or Verdigris.
Dirt or debris can often be removed through a gentle rinse.
PCGS Restoration will never add any substance to the surface of a coin.
Spots
Spots on coins can be the result of a variety of causes. Many spots can be removed, yet some cannot be removed without damaging the coin.
PCGS will not attempt to remove a spot unless it is determined that the spot significantly detracts from the coin's overall appearance or is active and will continue to grow.
PCGS will not attempt to restore a spotted coin if that in our opinion, a spot is so deep that removal would lower the coin's overall condition.
Older spots such as old spittle or old thumbprints often cannot be removed without stripping the coin's original surface and will not be attempted.
Newer contaminants such as recent fingerprints can be removed. Also, certain spots due to corrosive interactions can often be removed without impairing the surface.
Metal
PCGS Restoration will never add, remove or alter metal. This includes engaging in well-known “coin doctoring” practices such as smoothing, whizzing, polishing, engraving, etc.
Issues such as scratches, dings, planchet flaws or bending will not be addressed. If it is determined that a coin suffering from one or more of these problems does not have other issues that can be addressed through Restoration, the coin will be returned as is.

I know nothing about coins but that is ponderous. Seems overly nuanced from my vantage point.