Jeff Bezos sparked outrage moments after his return from space on Tuesday when he thanked Amazon’s customers and staff for helping him pay to get there. Mr Bezos, 57, who has an estimated fortune of more than $200 billion, said: “I want to thank every Amazon employee and every Amazon customer because you guys paid for all this.” The comments about Amazon – a company repeatedly criticised for exploiting its workers and avoiding taxes – prompted an immediate backlash on social media, with many users complaining Mr Bezos must be tone deaf. Elizabeth Warren, a US senator, said Mr Bezos “forgot to thank all the hard-working Americans who actually paid taxes to keep this country running while he and Amazon paid nothing”. The non-profit investigative journalism organisation ProPublica says Mr Bezos paid no income tax in 2007 and 2011. Robert Reich, former secretary of labour under US president Bill Clinton and a professor of public policy at the University of California, Berkeley, wrote on Twitter that Mr Bezos has crushed unionising attempts at Amazon for decades. “Amazon workers don’t need Bezos to thank them. They need him to stop union busting – and pay them what they deserve,” Mr Reich wrote. Mr Bezos stepped down as chief executive of the successful e-commerce company in July, allowing him more time for side projects including his space exploration company Blue Origin. He previously said he financed the rocket company by selling $1bn in Amazon stock each year. After the spaceflight, Mr Bezos awarded $100 million donations through a new philanthropic initiative to US chef Jose Andres and CNN contributor Van Jones to put towards any charity or non-profit group of their choice. Mr Jones has founded several non-profit organisations, while Mr Andres’s World Central Kitchen provides meals to people displaced by natural disasters. Nevertheless, Earl Blumenauer, a US politician who is on the tax-writing Ways and Means Committee, on Tuesday proposed legislation that would tax space travel for non-scientific research purposes. “Space exploration isn’t a tax-free holiday for the wealthy,” said Mr Blumenauer, a Democrat in the state of Oregon. “Just as normal Americans pay taxes when they buy airline tickets, billionaires who fly into space to produce nothing of scientific value should do the same, and then some.” After the successful flight, in which Mr Bezos and three other passengers blasted into space on board a Blue Origin rocket, the billionaire revealed his space tourism company had already taken $100m in bookings for coming launches. Blue Origin plans to carry out two flights for paying customers this year, with the number of journeys expected to increase thereafter.