The actual 'garage startup' is bit of a myth, played up as a rags to riches story. Most startups happen in personal spaces like bedrooms or home offices or rented offices and are often better funded than you might think. Or the 'garage' was just a very temporary thing and mostly for storage/laziness/clutter. Even Woz debunks this:
“The garage is a bit of a myth,” Wozniak told Businessweek. “We did no designs there, no breadboarding, no prototyping, no planning of products. We did no manufacturing there.”
Today a "garage startup" just really means they're just starting out, self-funding, or under-funded.