The husband of an Australian woman killed by a bus travelling at 70km/h in a 20km/h zone in Mexico last month has blamed her death on privately owned bus companies, whose drivers race each other to pick up customers before one another.

Kylie Nastasi and her husband Tony had just caught a bus to their Cancun resort on the last day of their trip before they were scheduled to fly back to Australia. In the end, they did fly home together - but 23 days later, in tragic circumstances.

Tragic end to holiday: Sydney couple Tony and Kylie Nastasi. Mrs Nastasi was killed by a speeding bus in Mexico.

Mr Nastasi said he and his wife were holding hands as they began to cross the road, which they had done every day, when he noticed a bus "30 or 40 metres" to his right-hand side.

"He [the bus driver] wasn't looking at us and I didn't realise he was doing 70km/h in a 20km/h zone," Mr Nastasi said. "We only had one lane to cross, but before I knew it he was on top of us. He didn't beep and he didn't skid.