In the case of Trump, my impression is he purposefully set out to undo anything Obama had done as some sort of weird, childish, vendetta. That aside, in general though I think these things happen because rulers are looking to reduce taxation for the rich, and things like "pandemic response team" are pretty well hidden from public view, and can usually blagged ("we kept 10 million face masks as an emergency reserve" fading to mention that's a day's worth, say, or that they were out of date, or not the right type of mask).
