I know nothing of how Ubers work as I have lived rurally for many years and they don't exist here !
My elderly father lives in an outer London borough and is giving up his car soon. His neighbours tell him that for short notice trips (shops etc) it is difficult to get taxis and they use Uber. How do they work and would it be simple enough for a mobile but relatively fragile and wobbly 84 yr old with limited tech skills and a slightly dodgy memory to manage ?