Well, it's us, the U.S.
We really like material possessions a lot
More so than people
I think it's pretty common in many countries, and throughout history, for people to be very concerned and focussed on material possessions, particularly in cases where it's a will that is being contested.
People can be focussed on having another persons property, despite their wishes, for a number of reasons. Whether it's attachment to that person, reliance on those possessions, or just greed.
I know there was a ruckus (although no legal proceedings), when my Nana died and she left myself and my two brothers in her will. And that was because she isn't biologically, or even legally related to us. She was a very close family friend of my grandparents, and she was essentially involved in bringing up my mother and her sister, and then bringing up myself and my brothers. She described us in her will as her "adopted grandchildren".
She left us 1 or 2% (can't remember which) of her estate each, which was about £5000.
The rest of her family, who hadn't spoken to her or seen her in years, or constantly fought with her, were very angry that 3/6% of her estate was being given away to people not related to her.
Despite the fact that they were being left with either an estate of £235,000 or £485,000 to be split between them.
Basically, people will be quite happy to contest wills when they think they're missing out on something they can get.
But there are cases where people are cut out who probably shouldn't be, or where a will hasn't been left and someone close to the individual is neglected entirely.