The development of autonomous electric vehicles for use on U.S. roads seems to have hit another snag.

When General Motors decided to cancel its appearance at the closely watched Consumer Electronics Show, a GM spokesman said the company ran out of time to finish the car it hoped to unveil. It laid the blame for its failure on the United Auto Workers strike that idled plants for 40 days last fall. A plan to have GM Chairman and CEO Mary Barra speak at the event was also scrapped.

GM didn’t announce which specific model affected its plans, but industry watchers had speculated for some time that the company intended to reveal an autonomous electric vehicle at the show. The annual electronic innovation show has been a mainstay of the domestic automaker’s public relations strategies in recent years.

However, because they are less-saddled with the reputation of being old fashioned, throwback companies, CES is no longer the priority for the “Big 3” that it once was. Another issue is that hundreds of companies across all product categories compete for the attention of consumers and the press at the annual show. It’s easy to get lost in the crowd in that kind of environment. Instead, carmakers have relied more on private events, where they have full control, to showcase new products and technologies.

Still, GM’s decision to pull out raised some eyebrows. It seemed to be yet another example of the difficulties it, and other car companies, have had perfecting the self- driving, semi- and wholly-autonomous vehicles of the future.

Recently, Barra and U.S. Transportation Secretary Elaine Chao met to discuss a filing GM made requesting permission to make available street-ready, autonomous vehicles for its package-delivery fleet customers.

After the meeting, Chao opined that perhaps auto sector analysts, and industry leaders, were being “too optimistic” about when fully autonomous vehicles could be safely deployed. A final decision on the GM petition is expected soon. Still, it’s increasingly clear that the complexities of developing autonomous electric vehicles are greater than most experts assumed.

The future, at least as it pertains to the development of fully autonomous vehicles, might be further away than most people thought.