While it sees like this would be a great way for homeowners to demonstrate that they have accounted for and included the ultimate accommodations for accessibility, visitability, comfort, convenience, safety, security, sustainability, and other characteristics associated with good universal design techniques, a standardized rating system is not practical - for several important reasons.
One has to do with the design of the home itself - and its age and architectural significance. Many homes simply cannot be modified - without a tremendous amount of cost and effort - to include a more reasonable entrance, elimination of steps, and better access route trough the home. In some cases, the architectural integrity of the neighborhood would suffer, This doesn't mean they can't score well in other areas, but there is no way they could score an acceptable rating for the entrance and approach.
Of course, budget is the main defining criteria on what changes can be considered and undertaken. Depending on the endgame and what one wants to spend to achieve it, they are many design changes that can be made in a home. Some will be desirable and readily embraced. Others will be less apparent to the owners.
This does not mean we shouldn't attempt to make as many changes as the owner wants or allows, as many as they can afford, and ones that will help the home to live better for everyone involved. It might mean a much smaller scale approach that what we would recommend or select with a larger budget or without worrying about accommodating the residents while they continue to live in the home.
The real point is that all home modifications are personal. There might be guidelines and standards that we want to achieve, follow, or emulate. Still, it comes down to what serves people the best in their home. Remember that in most cases, remodeling or renovating is purely an elective activity that is done consciously by the owner.
How they choose to approach this, what they set aside to invest in the project, and what they desire to achieve is entirely up to them - with some coaching and guidance from us as to what will help them enjoy their living space more and be safer in it.
Additionally, some homes are going to have a better starting point than others. Let's say there were 20 items that had been selected that every home should include or possess to make it a universal design home in the most basic sense. What if it already had five or six of them (or more)? Does it get credit for those? Does it have to add twenty more to the ones already present? Does it receive some sort of label or distinction for the items already included - even if no more are contemplated or undertaken?
What if a home already has several universal design features in it, but only a few of the items included in the list of essential items to have? How are the features on the list allocated? How many are on the outside of the home, how many apply to doorways, passageways, and windows? How many involve the kitchen area? The bath? Bedrooms? Closets? Laundry areas? Having a list of items by which to measure how well a home provides universal design features and attributes might well be a function of the person or people assembling the list and what they expect in a home rather than being a good cross-section of on an effective home.
Would the list focus on items that make a home safe, ones that make it accessible, ones that offer security, ones that provide comfort or convenience, ones that focus on another area of the home, or a blend of these qualities?
Having an objective list of criteria by which we could measure how well a home had provided universal design features might seem to be desirable if it was possible to create such a template, but deciding on the minimum number of items to include, overlooking design peculiarities among various homes (due to their age, location, layout, and style), ignoring budgetary requirements, advancing a checklist that would need to apply across the country (or an even larger geography), and taking the individual and their preferences and needs out of the equation would make this a very substantial undertaking.