The cost of acquiring new customers once they reached scale was the issue. The cost went up significantly making their unity economics unfavourable.

Back the day I had a short stint at Flixbus in Germany. Being an ops / logistics guy I wasn't that impressed by their operations at the team I was at (their line business seemed different but grew out of one of Flixbus earlier acquisitions, mein fernbus). Also the tech didn't look revolutionary. What was top notch, and backed by serious money, was advertising and marketing. They had all the metrics, the strategy, the budget, knew the processes, everything.

It was that what gave them the market penetration in new countries, out spending and out performing competition until competition faulted or was bought out. So, the lesson I took, was that a lot of the latest b2c e-commerce start-ups are to a very large extent marketing driven.

It's easy to measure an LTV that doesn't turn out to be accurate many months later.