I
do check that they are reliable (well, mostly reliable) every day. I do so through life experience. This isn't done in a
foundationalist way, but rather in a
coherentist way, at least in part.
When everything that I experience confirms that my senses are senses, and that my mind is capable of understanding, that
is support for the idea that I am capable of sensing and reasoning, and there is no significant reason to doubt this. That is a firm and justified trust. It's not true that one must "prove" that one can see in order to "check" and "test" one's sight against the broad spectrum of one's experiences.
Likewise, if I don't have any good reason to think that I could be in some Matrix, there is no gravitas to concerns that what I see isn't just some manufactured illusion. The sort of concerns that you have fall into this sort of solipsistic trap. It's a needless one.
eudaimonia,
Mark