I used to date a girl who had a Galaxy S8 from sprint and that phone had most ridiculous ads like online casino ads, everywhere, even on lock screen.
A few years back Lockscreen was identified as one of the most underutilized real estate on the mobile phone. So a lot of phone companies started selling it to the highest bidder. While Samsung shouldn't be needing it, a lot of the lower end Chinese companies make razor thin margins on the phones, even if a company offered $1-3 for pre-installing an always running app that would show ads to users, they'd happily take…
Yeah, fuck that.
But a less tech savvy person might just go "well this is fine, I guess that's just how it is", and live with it.