Let me prefix this by saying that I don't necessarily support implementing a UBI system. However, I have yet to see anything called a "basic income" or "universal basic incomie" pilot program actually do things at all correctly. As other commenters have suggested, these pilot programs seem to be designed so that they must necessarily fail and be examples the politicians can point at and say, "See? We tried it and it failed." I'm not convinced UBI can actually work, but it definitely won't work if it isn't done right.
To do UBI correctly, it has to go to everybody. And it has to *replace* any income support programs. That is, it has to replace government programs such as (un)employment insurance, government pension plans not funded completely and directly by member contributions (because everyone would get UBI, the pension plan wouldn't be required, would it?). There also can't be any clawback because someone earned some money outside of the program. Doing that just adds administrative cost to the program and discourages recipients from working. Also, every person should get the same amount regardless of age, marital status, etc., though maybe with a minimum age before it kicks in. Otherwise, you recreate existing complex administration processes.
Now, here's the absolutely critical component. This UBI must not be set at a level where the recipient can afford a car, nice television, nice house, 127 cats, and the like. It should provide for *healthy* subsistence in a reasonable market and require careful management of money to do so (which encourages those who won't work to move out of the expensive cities like Vancouver or Toronto and those who want a nicer standard of living to work). It needs to be set such that if you want a nice living, you have to earn additional money, on which you pay taxes. (Also, under a proper UBI system, only the UBI itself would be income tax exempt. There would be no need for low end tax brackets under such a system.)
Limited pilot programs just aren't going to demonstrate anything because they're not going to work exclusive of existing income support programs and are going to potentially unbalance the labour force because the people getting free money can work for less. (That's probably why the clawback had to be there in this case.) To truly demonstrate whether such a system can work, it has to be tried at a fairly large scale and *existing* income support programs must be suspended for anyone participating in such a test.
Now I do understand that there is always going to be someone who isn't well served by such a program. But that's true of all the current options, too. If you're going to insist that it has to be perfect for everyone, then are you willing to give up all the existing social programs that you currently benefit from on that same principle? I thought not. So let's not create strawmen out of extreme edge cases since *every* system has those.