You find all sorts of examples of people independently discovering things at the same time, and this isn't just coincidence. Maybe most famously is Leibniz vs Newton creating calculus. The pieces were all in place for the mathematical study of change. The outcome wasn't predestined, each man's creation was quite different in ways, but they accomplished something that was ready to be accomplished.
Whether it's physics or technology, nature abhors a vacuum. Unexploited niches get filled. Sometimes in significantly different directions, but very often the outcome is strongly influenced by the opportunity.
In biology, this is a bit like convergent evolution. The implementation details aren't predestined, but general solutions to environmental problems _are_. Eyes and legs are very useful things to have, and they're nearly ubiquitous.
With Tesla, the deal is that we know we're going to run out of oil, and pollution sucks. Developing an alternative has been a big talking point since the 90s, and there are a whole lot of players in the game. Lots of companies are making lots of attempts and have been trying many different technologies. Lithium batteries are winning the technology race, they developed because of other consumer electronics and the environment is best for them. It's just evolution. Many other companies are trying different things and the same thing, it's not driven by copying Tesla (the competition helps though) it's driven by the niche need for a solution expanding and becoming more and more possible.
The variables are implementation details (fuel cells? lithium batteries? something else?) and timing. There can be quite a lot of uncertainty with "how" and "when" but quite a lot less with "if".