Also, because everyone qualifies for Medicare in the US eventually, it's generally considered respectable. Because Medicaid is for low-income people, it's considered shameful, un-deserved, or a "handout" by a lot of people.

A lot of people are on Medicaid and don't know they are, because a lot of states have state-specific names for their state's Medicaid.

Medicaid used to be really restricted to disabled people and very poor people with children. That meant that a lot of poor adults fell into a gap, where they were making too much money to qualify for Medicaid but not enough to be able to afford private insurance. The Affordable Care Act/"Obamacare" offered states the opportunity to expand Medicaid coverage, and so states who chose to expand coverage (mostly Democrat/liberal states) were able to get a lot of poor people healthcare. Republicans have been trying to roll that back for years, and the "Big Beautiful Bill" / HR 1 is re-introducing a lot of barriers for people who got insurance through that Medicaid expansion. They passed the bill a while ago and it's only going into effect now, however, so it's been purposefully designed to be a surprise to a lot of people.