The "sense of duty" argument sort of works for Will, since he was born into it and raised with a huge weight of expectation and responsibility since birth, but how does it apply to Kate?
If Kate didn't want the massive responsibility of having to occasionally go and shake hands and be made a fuss of (or go to Wimbledon or a celeb party and include it in their work event numbers) she shouldn't have stalked William for years then hung on for dear life for ten years trying to get him to marry her - and pointedly not working - just because she was desperate to be queen.
Kate isn't some naïf like Diana, seduced into joining the RF as a vulnerable teenage girl. She was a nearly 30-year-old woman and had seen life as a Royal first hand for more than ten years when she got married, and she's the one who did all the chasing. She knew the score, was given the easiest ride available (all those years of being allowed to live quietly in Wales/London and not work, all those years of positive media campaigns promising Kate was really keen/doing princess training/deffo about to start working hard next year next year next year) and yet still, after 20 years, doesn't even do the bare minimum.
I don't blame them for going to Norfolk but this pandemic should have been an easy PR win for the royals and the modern day equivalent of the RF remaining in London during WWII and the Queen working as a mechanic and a volunteer truck driver. That showed genuine grit and dedication and a willingness to get stuck in and be humble. And due to the fact the current crisis is not a war but a viral contagion they didn't even need to do what the Queen did and literally get their hands dirty (quite the opposite lol!). If all the senior royals had just visibly stayed home, supported and promoted the government's messages and rules rather than doing stupid shit like prancing all over the country maskless or travelling to Scotland after testing positive, and made better use of social media and video technology, they could have turned whole thing to their favour. I can't remember when the RF has fucked up so badly or caused more bad feeling and negative PR.