What is Algernon trying to say when he says...
"Lane's views on marriage seem somewhat lax Really if the lower orders dont set us a good example what on earth is the use of them? They seem as a class to have absolutely no sense of moral responsibilty".
Lane is Algernon's self-depricating servant. He serves as the eiron (character who thinks he is lower than he really is), a comic foil to Algernon's alazon (character who thinks he is better than he really is).
Verbal irony is key in Wilde. So, Lane works by understatement and Algernon works by overstatement (hyperbole). Witness the exchange before this:
ALGERNON: I don't know that I am much interested in your family life, Lane.
LANE. No, sir; it is not a very interesting subject. I never think of it myself. (understatement)
And so, after Lane leaves, Algernon delivers this mini-soliloquy/aside to the audience. It's classic overstatement, a funny statement because we have a member of high society making a condescending remark about the lower classes, when all the while the audience knows that Algernon has very little moral responsibility himself. He owe's money, changes his name, lies about his whereabouts. Also, of course, it's an unmarried man giving an older happily married man advice about marriage.
Algernon is speaking for Wilde here. The statement satirizes the elitist, self-styled, and arrogant nature of the British upper-class, many of whom would have been in the audience laughing at themselves.