I see bikes like this all the time at the bike rack where I work. One guy rides a steel Huffy mountain bike that must be at least 15 years old. The paint is cracked and there is rust in spots. The brakes, deraileurs, and everything else on the bike looks to be original and still functional. He rides it year round, after the full carbon race bikes have been stored away for the winter. One thing I find funny is the bike has a "Made in USA, Lifetime Warrantee" sticker. High end bike manfacturers insist they need to manufacture $2k+ frames in China these days.
I've seen several other bikes from places like Target, Walmart, etc. Guys get to work on them day in, day out.
I remember a thread, I think on Usenet, where a guy bought a walmart bike for commuting, and then did a cost analysis of what it cost him to keep the bike going versus cost of commuting by car. I wish I could find the thread, but I think he ended up breaking even in about 3 months and the bike turned out to be pretty reliable. The important part is to keep bearings greased, bolts torqued down, and the deraileurs and brakes adjusted.