Tom wrote:

the elderly lady who loves nearby has fingers that are gnarled with rheumatoid
arthritis. Meanwhile, electric hedge clippers these days are made with
triggers that take a lot more force than years ago - and so does the
thumb-operated catch that lets you lock the clipper into the 'on' position.

Is there any way to make it easier for her?

The problem here is that if the person lacks the hand strength to
operate the safety device, they probably also lack the hand strength to
safely operate the device.