Some people are going to need assistance at the entrance to their home - the approach, walkway, porch or stoop, lighting, entrance doorway, door hardware, and security. Others are going to have a lesser need or perhaps no need in this area. While it's common for homes to be deficient at the entrance, not all of them are. This applies regardless of the physical needs and requirements of the occupants of the homes, but their condition may highlight work that needs to be done.
This is the entire point of rejecting a uniform or universal set of criteria for conducting aging in place renovations. Even with trying to meet universal design or visitability objectives, not every home or every individual will require the same approach. Some homes will already have the desired improvements. Some budgets just won't allow an approach as extensive as others.
Moving on to others areas of the home - hallways, closets, doorways, kitchens, bathrooms, and other areas - the same is going to be true. Each home is going to be different and have various needs. Some will be able to serve the needs of the occupants better than others. Again, budget, age of the structure, and work that already may have been done will be mitigating factors in deciding how to approach any renovations. Then, the physical needs, requirements, and desires of the people occupying that space will further refine what should and could be done to make the space more effective and efficient for those living there.
If there were to be any set of criteria that we would attempt to apply across homes that we work with, the range of physical ability alone in the people that we want to serve varies so much. Some people have no urgent medical needs or requirements but may have mobility or sensory limitations that come with aging that may not require any specific modifications to accommodate them but would be happier with homes that make it easier for them to navigate them.