Why does that logic not apply to those on higher incomes? Have a job with a free-market rate of $100/hr? Why not work for only 30 hrs a week? Also, UBI levels

Why does that logic not apply to those on higher incomes? Have a job with a free-market rate of $100/hr? Why not work for only 30 hrs a week? Also, UBI levels are never proposed at $3k/week ($150k/yr), but rather at about $250/wk ($13k/yr), or only 2-3 hours of work per week for the $100/hr guy.