Yeah, you can always buy a refundable fare in the case of airlines, but often it costs so much more than the non-refundable fare that it is not worth it unless you think there is an extremely high likelihood of you having to change plans (and even then, it may just make sense to wait until the very last minute to buy rather than paying $ for a refundable ticket). Some airlines are more reasonable than others (for instance, all of Southwest's fares are exchangeable, and the refundable fares have seemed significantly less than other airlines when I've looked for a refundable ticket). However, when I've searched for refundable coach fares for domestic flights, I often come up with fares upwards of $1000 round-trip, which seems a tad absurd when the non-refundable fare is less than half that.
I will say that this is one of the reasons I really like Amtrak (though I really like the LD trip experience in and of itself) - I can change last minute and not have to pay some change fee or pay ungodly sums for a refundable ticket. In fact, I just had to eat the cost of a plane ticket due to taking the trip to New Orleans from San Diego at the last minute (and thus not being in CA to make my flight back to Michigan, and instead taking the City of New Orleans back) - the ticket was worth $157, and the change fee is $150. I guess I technically have $7 in Delta credit I can use, but I see no scenario in which I'd use it before it expires (and $7 is basically nothing)...