Clearly, a life of dependency on the government is not literal slavery – but is the metaphor / comparison valid? I’ll state my view (which is basically “no”), and people can disagree (or whatever) in the comments.
The essence of slavery is lack of self-ownership. You’re someone else’s property in a direct way, where they tell you what to do, seize all the products of your labor, and violate your body (or worse) at their option.
Excepting criminals (people deprived of rights under due process and for heinous acts), I think that if the government can either conscript your labor, or seize more than half of the product (the wealth/income) of your labor – and jail you or worse, if you don’t comply to the government’s satisfaction – then metaphors/comparisons of slavery begin to apply. Because the conditions for slavery have been met in part, even if the government gives you “freeman” status and a lot of lifestyle choices.
One of the lifestyle choices that you face, as a non-slave, is the extent to which you live off of government-provided benefits – in other words, the extent & duration of your being a government dependent. I don’t think that government dependents can be compared to slaves. Because, while the dependent may indeed be lulled into a lifestyle which is passive, limited and degraded, they still keep the right/option to change and become less dependent.
Thus, comparisons to slavery may be valid when speaking of government mandates on people, oppressive levels of taxation, and denials of rights (e.g., right of free speech). That is why we speak of Communist nations as “slave nations” and so forth.
But it’s not valid to compare voluntary government dependency to being a slave. If anything, the person who lives a lifetime of voluntary dependency on the government is closer to being a slave-master; someone who (partly, or metaphorically) uses other people as slaves.
And that would be another reason that I find fault with Cliven Bundy’s recent remarks. (While defending, of course, his right to make them – and the pro-liberty movement in general.)
To suggest that government dependents are like slaves is to suggest that their dependency isn’t voluntary. In other words, it’s to suggest that government dependents somehow didn’t choose their situation. And if you really believe that, then you deny their natural human power of choice; you believe implicitly that they are sub-human, or the moral equivalent of children. And I don’t believe that.
The people who are partly like slaves are not the government dependents, but rather, the productive working people whom the government forces to pay for its dependents.