i'm always confused by "grandparents" since that can mean people who are 50 and no where near retiring or people who are 100
this is just a quick note on cast iron.
is the "uneven" that the pan is warped? which is really hard to do to a real iron or carbon steal pan.
and no cast iron finishes will not survive say a whole lot of canned tomatoes -
it's quite possible to revitalise a cast iron pan - if it's gunky - there are a bunch of youtube vids, but one way i use frequently is heat up the pan, put in baking soda and enough water to cover the baking soda and let it go for a bit.
Then steal wool (with rubber gloves on) - when cooled enough to touch - you'll get all the gunk off and alot of that black finish.
when you're happy with that state, you can rebuild that non-stick surface using a high heat oil like flax or rice bran - again many you tube vids on applying the oil to a warm pan, wiping it off or really buffing it in to get it to the thinnest layer possible, putting it into the oven at high heat for an hour - and repeating - or just cooking with it to rebuild the surface.
the oil at high heat polymerises - forms a bond with the pan - and creates that nice surface.
so if they want to save their pan there are ways.
you never ever need to replace a cast iron pan and you never have the risk of overheating a coating which is plastic - and having that get into your bod.
hope that helps
as for PART 2 (new bit)
all-clad stainless is lovely - it doesn't do coating - it just uses oil or whatever fat you like for moving food around.
Aluminum is sometimes found (ok often found) in say skillets in restaurant kitchens. It's light and cheap and likewise uses oils - so it's not non-stick. But it's also really light.
There have been concerns about cooking with aluminum for fear of toxicity from aluminum.
ALSO FOR INDUCTION ALUMINIMUM is right out and you need to check if the teflon pans have an induction-ready base.
Carbon steel/cast iron - they work fine. Think: will a magnet stick to this? if not, it's no go on induction
Cast iron is pretty fool proof and it can be cheap but heavy like logde or it can be lighter, spun, like netherton foundry (https://www.netherton-foundry.co.uk/iron-frying-pans)
Carbon steel likewise is a kind of iron cookware that may be a little more even in heating, a little more pricey but not much -(https://carbonsteelcookware.com/de-buyer/)
carbon steel and cast iron also need to be seasoned.
The teflonn stuff - well that teflon dies over time and the base is aluminum so while it's fresh if you never overheat it (cook on high) you may not be getting plastics into your system.
so there are risks/trade offs in terms of weight of pans, materials, etc.
If you figure out what your grandparents like to cook, then it's easier to help come up with a set of things that will work for them, and they can feel happy using.
so checklist might be:
what do you like to cook?
for asian cooking a single thin carbon steal wok is easy if they're happy cooking with oil. They season it - many youtube vids - and they're don.
after that, a good sharp knife and you're away. if you get one with a lid, super.