Why do mobile phones have app platforms and landline phones don’t?

It really isn’t easy to find a home phone these days. Whilst we have loads of mobile phone shops, hardly anyone stocks a simple land line phone anymore. Why is that?

And, more to the point, why is it that land line phones haven’t evolved in the same way that mobiles have? I managed to find two Android powered home phones, but both had bad reviews that really put me off. But seriously, two smart-home phones? Is that all? Is there really no market for something more advanced in the home? I find it very strange indeed.