I'm positive that this answer won't be appetizing if you belong to the dyed in the wool, coastal progressive contingent, heavily represented here on HN.

Given the recent political developments (not just here in the U.S. but across the world including Europe), it is high time we speak frankly and not say things couched in vain pleasantries, suited to people who'd rather not hear or say anything disagreeable, to keep up appearances.

Having said that, if you want the honest truth as to why _some_ people may have an objection I'm willing to explain.

People who are unlucky to be earning just enough to be excluded in one way or the other, from these UBI handouts ( which already happen in disguised means and forms, but more on that later [1] ) but not enough - from their wages & other sources of income - to be living a comfortable life will find themselves asking how is it that suddenly

a) their kids cannot get into those choice daycare centers which weren't so crammed only a few years ago
b) the economy classes on most flights are filled with the riffraff & people from outside of the income/social
classes they're accustomed to
c) their favorite restaurants are always booked or have lines out the door ( a perennial theme in SF ) [2]
d) the rent pressure is greater for a smaller inventory of listings in the desirable neighborhoods
e) their friends cannot afford to socialize as frequently as they once did ( or worse, have moved to a different part of the
country simply because it is no longer affordable to remain ) due to the same wage pressures

In other words people are mostly fine with any entitlements to the poor & disadvantaged as long as it doesn't threaten their way of life or become a competitive element to the comforts & privileges they are accustomed to.

Once those things are threatened people find it difficult to accommodate those things, even if it makes numerical sense - as in say an universal extra $10,000 bump to _absolutely everyone_ regardless of income class ( if that is what they even _mean_ when they say UBI; I doubt it is ) might only mean that Person X can send his kids to a much more exclusive summer camp every year but now that same bump in income means more crowded classrooms for the same kids during the rest of the year because Person Y can now afford to send his or her kids to the school for privileged kids.

More directly - and less politely - people don't want a handout-receiver ( and how you define that term depends on your political slant and can mean anyone from a lowly UBI claimant to a loftily paid city worker in any large progressive city[2] ) suddenly being able to afford the same niceties of life that they see themselves slaving at their 9-to-5s for.

Economists and policy makers can couch it in clever speak but it really is that simple.

[1] S.F. spends record $241 million on homeless, can’t track results
http://www.sfchronicle.com/bayarea/article/S-F-spends-record...

[2] Report: San Francisco has the highest density of restaurants in America, by far
http://insidescoopsf.sfgate.com/blog/2012/08/01/report-san-f...

[3] This San Francisco Janitor Made More Than $270,000 Last Year
http://time.com/4555692/san-francisco-bart-janitor-salary/