this has already happened in the food service industry. McDonalds used to hire a lot of teenagers; for many it was their first job. When minimum wage went up sufficiently high enough they replaced human labour with self-serve kiosks and reduced staff to a single register and kitchen staff. Tim Hortons switched to centralized bakeries and terminated all store-level bakers.
I'm not arguing either side of this, just that there are very real impacts. It's not a situation where every entry-level job is going to be floated by a rising tide, some people will drown.
As a Canadian - I can comment that Tim Hortons has notoriously terrible baked goods. You might grab a breakfast sandwich there (and a lot of people are weirdly enamored with their coffee) but they can't even compete when it comes to baked goods in most metro areas - they're a coffee shop and we have much better alternatives for baked goods. The cost to them for cutting bakers was to gradually lose their position as a purveyor of donuts in Canada.
Can we blame that on minimum wages going up, or can we blame it on McDonald's find a cost-effective way to automate that? Do we find no kiosk in those states who haven't had a minimum wage hike?
Turning your example around: if those teens were to receive UBI and McDonalds could hire them for only $3/hour instead of having to pay them full wage, some of the self-service kiosks might not have appeared, and the customers might have encountered better motivated workers?
The U in UBI stands for universal: everyone gets the same amount, regardless of whether they have a job. Taking a job is additive with UBI, there is no "significantly less money".
Under UBI, a government could do away with minimum wage completely because there is no coercion by necessity. The employer only needs to pay enough to make it worthwhile for the employee to show up.
Some short-term unemployment insurance would likely still exist under UBI - the two programs have sharply different goals, and a viable UBI would generally be too low for a "full" income. But UBI would almost certainly allow for more flexibility in the labor market, that would make extended UI a lot less relevant.
That only follows with a theoretically perfect UBI which either matches everyone at the highest COL or matches everyone with their local COL and reacts instantaneously with increases due to changes in the market.
If there is a delay in UBI increases, or if the UBI is not properly matched to the COL, there will still be pockets of people who must work by necessity.
> The employer only needs to pay enough to make it worthwhile for the employee to show up.
That's exactly my point—why would you show up to a job that pays you less than you receive by default? It doesn't make sense to go from working 0 hours to working 40 for a less than 50% increase in income.
I'm not arguing either side of this, just that there are very real impacts. It's not a situation where every entry-level job is going to be floated by a rising tide, some people will drown.