if software development was like bridge-building

I was thinking recently about metaphors for software development. There are lots of metaphors, my favorite being the garden metaphor, but I've also heard software development compared to bridge-building. To me the comparison is wildly inaccurate, and for fun I decided to develop the analogy farther.

Building a typical enterprise software tool as a replacement for the Golden Gate Bridge:

• Before building starts, the designers debate for weeks over whether the bridge should be made of steel, plastic, or air gel. The virtues of air gel are touted with great smugness and the steel advocates are shown to be woefully behind the times. Nobody takes the plastic advocates seriously.
• A month into construction, the width of the Golden Gate channel doubles, and the rock underneath changes from granite to crushed gravel. Construction is delayed for a month while the bridge is redesigned. Air gel is found to be inadequate and the builders switch back to steel.
• Two months into construction, a freak electrical storm causes the bridge to entirely disappear. Construction resumes again after much wailing, finger-pointing, and an off-site backup bridge is created in Oakland.
• A week later another freak electrical storm causes the bridge to disappear again, but it's restored from the Oakland backup without mishap.
• At 75% completion it's discovered that the road bed will collapse whenever a Toyota drives on the bridge. The builders explain that Toyotas were never meant to cross bridges in the first place. Toyota drivers are directed to the Sausalito ferry.
• On the first day of active service, a last-minute Beatles reunion concert is scheduled in Napa Valley, causing the entire population of San Francisco to mob the bridge all at once. The bridge disappears and reappears four hours later. Everyone misses the concert.
• A year after the bridge is completed, the rock under the channel is upgraded from crushed gravel to decomposed granite. The bridge sits at a funny angle for six months until the foundations are rebuilt.

See what I mean?