Steam buses were operating in Engmand in the 1830s - Why then is the first car only built in the 1880s?

In the 1830s, steam-powered buses began appearing on British city streets. They were taxed out of the market and disappeared for a few decades, but that's besides the point.

Why then, if we could build a mechanically-powered bus in 1830, did the first car only appear 50 years later?