There already are Standards from ASABE / SAE on the various Categories of 3-point hitches and implements and separate Standards for 3-point hitch Quick Couplers and Quick-Coupler compatible implements. Various manufacturers have recently started complying with the Category I Quick Hitch Standards due to the rise in popularity of compact utility tractors for the homeowner market. If they do comply, they will clearly say so in advertising and/or Operators Manuals because it is now a "selling point." The John Deere Category I Quick-Coupler complies with the QC Standard and John Deere uses the specific name "I-Match" to refer to it. Some other brands of Quick Couplers also comply or at least can be adjusted to comply with the Standard.
However, for implements, you need to check carefully if they are compatible with the Category I Quick-Coupler Standard or not. Older John Deere and most others are not generally compatible with the QC Standard even though they are compatible with the general 3-point hitch Standards. In other words, just because the implement says it is Cat I does not necessarily mean that it will work with a Category I Quick Hitch.
For some implements that do not meet the Cat I Quick-Coupler Standard, simple modifications can be done that make them usable. This usually requires some cutting and welding for the top mast in particular. For other implements it may be quite difficult or impossible.
If you have any doubt, try the implement out with your Quick-Coupler before buying. It is not that hard to remove it from the tractor and take it (along with the sleeves and/or ball joint sockets) to the location of the implement you are considering.
Many of the Frontier Implements are manufactured for John Deere by Woods. Those painted Woods orange that have direct counterparts sold as green under the Frontier label do meet the QC Standard.
As time goes by, it is likely that more and more compliance with the QC standard will occur. After all it does not cost the manufacturer more to design and manufacture the implement hitch to meet the QC Standard.
Hope this helps.
JackIL