It is amazing how autonomous vehicles have transformed from simple beginnings to complex systems that we witness today. The story begins in the 1920s and 1930s through basic tests with radio-controlled vehicles. Though primitive, these early attempts laid the groundwork for the monumental strides we are seeing today.

A notable milestone was the DARPA Grand Challenge of the early 2000 which marked a turning point that expanded the possibilities of what could be achieved. Then came Google’s self-driving car project that popularized autonomous vehicles. With progress in AI, machine learning, and sensor technologies; these vehicles not only remain dreams but are becoming practical initiatives.

One thing I find most fascinating is their potential for mobility and accessibility enhancement. The possibility of drastically reducing traffic accidents arising from human error is a significant gain for road safety. These cars also present novel transportation options for senior citizens and handicapped people thus assisting them to live independently and inclusively.

The economic and employment impacts of autonomous vehicles showcase the potential for new opportunities in tech, maintenance, urban planning, AI, and cybersecurity. The process might be challenging; though the long-term benefits may be significant.

From an environmental perspective, autonomous vehicles offer a promising avenue to reducing emissions through optimizing driving patterns. This sustainable transport system could lead to less traffic congestion as well as an eco-friendly transportation system. Moreover, these cars assist in sustainable town planning by decreasing parking needs and increasing green spaces.

Despite this, several obstacles continue to bar the acceptance of self-governing vehicles on a large scale. Ethical issues including decision-making in cases where accidents cannot be avoided have huge implications. It is also essential to develop strong regulatory systems for safety, privacy, and conformity across jurisdictions.

To sum up, autonomous cars are much more than technological breakthroughs; instead, they mark a paradigmatic departure in transportation philosophies. The possibilities that they present about security, accessibility, and sustainability are overwhelming; but navigating the ethical, economic, and regulatory challenges will be key to realizing this future.