I think you are being somewhat unfair on the Samsung Fold line given that is clear they have tried to stay sub $2000 yet every year have spent considerable R&D developing the hinge and folding screen that does not translate as obvious spec bumps to most. When you are doing this there is little room for other spec bumps.
There is good reason even Apple have to buy their screens from Samsung.
When your only producing 5-10M units a year the same economies of scale do not apply and Apple is the one who's really lagging IMO.
Sure some other Chinese OEM's are pumping out similar folding devices with ish higher spec's but then again I can buy a cloned Rolex for $75, so it it really a like for like comparison
It's not lack of competition holding back the Folds, it's sales and Samsung despite all the criticism its had over the last 6/7 years continues to take the risk and invest in Folds where Apple only joins the party possibly next year.