Brain wiring of fine motor skills (like the muscles that control our tongues) is very natural for babies when they learn their first language. It gets harder as we get older. Still, even at the age of 8 a child can learn how to ride a bike. An adult can still learn to swim. Most of us learn how to drive a car. Even at the age of 50 or 70 one can learn to play the piano. But it requires more effort.
The easiest sounds are “a” and “m” and they are present in every language in the world and we are talking thousands of languages here. The easy sounds are usually among the first for a baby to pick up. Then they progress to less common somewhat more difficult sounds like “n” or “b”. The “r” sounds belong to one of the most difficult sounds that exist. The article below will explain all the details.
You can learn and speak Italian without ever having to master the alveolar trill. The good news is there’s only one phoneme, so no ambiguities. The Italians will understand you.
“The alveolar trill is a type of consonantal sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents dental, alveolar, and postalveolar trills is [r]. It is informally and commonly called the rolling R or rolled R. Quite often, /r/ is used in phonemic transcriptions (especially those found in dictionaries) of languages like English and German that have rhotic consonants that are not an alveolar trill. This is partly due to ease of typesetting and partly because <r> is often the symbol used for the orthographies of such languages.
In the majority of Indo-European languages, this sound is at least occasionally allophonic with an alveolar tap [ɾ], particularly in unstressed positions. Exceptions to this include Catalan, Spanish, and Albanian, which treat them as separate phonemes.
http://en.wikipedia.org/wiki/Alveolar_trill