Who bears the cost ?
You say it'll be more expensive
The real question is ''who bears the cost?'' The answer is ''not the development organisation'', eg not the vendor but its customers. So the benefit to who has to pay the extra cost for the reliability gains little, a bit less work for its call center maybe, but that is about it. Its customers however: waste huge amounts of time on work arounds or become frustrated - but does the vendor care ?
The other cost of producing reliable programs is time. The extra time taken means that the competition might get their product to market first and so get the customers and maybe even the market. One company that has used this ''get something that vaguely works and let the customers suffer'' method is Microsoft; it did this in its early days, got better for a while and is now getting worse again.
Another part of the problem is that customers getting redress is rare. We are pushed to accept major bugs. It is hard for the customer to go elsewhere, they have already made an investment, changing is costly - and anyway: will the competition be much better ? Probably not: commercial factors dictate not.