My experience: using paypal is so confusing for me, compared to alipay. And ebay makes you uncomfortable and doubting your purchase decision more than taobao.

I think it partially explains Alibaba's success in China. how you do shopping and paying is very much dependent on the "tradition" and regulation environment, and a local company can optimize that better than a global one.

Aliexpress is a mess though, i agree with that. But I think the language barrier faced by the shop owners there may be the biggest problem.