This is often the case, as other non-native speakers tend to not use idiomatic language and use a limited range of vocabulary. Students who study English as a second or foreign language tend to communicate their ideas with few cultural references. You certainly wouldn't expect German and Japanese businessmen to use sporting idioms from US culture to communicate their ideas about a sales campaign. Another important point is that non-native speakers of are usually more patient with each other when it comes to variations in pronunciation. All of these factors work together to help non-native speakers have a relatively easy time when communicating with amongst themselves.
Native speakers seem to speak English differently.
Native speakers' use of the language often reflects their own cultural bias. They bring standard idioms into play that, in their own environment, seem perfectly natural. They often prefer a highly idiomatic use of the language. Phrasal verbs and slang creep into their expressions. These minor issues quickly become overwhelming to non-native speakers who are used to standard forms.