According to Google Trends, Chile is the #3 country in the world where Morrissey is most popular, edging out Mexico. If you put Morrissey head-to-head against Johnny Marr , Morrissey wins 97% to 3% for Google search interest in Chile.
Those percentages are similar across the world, and Marr is not popular at all in South America or Mexico. Which is why when Marr has played South America it's in multi-band festivals (e.g. Lollapalooza Brazil 2014).
Marr would be headlining shows in Chile if he were anywhere near as popular there as Morrissey. But he's not. That's not a knock, just a reality check. His post-Smiths music has not connected with people like Morrissey's has, and maybe he doesn't care. They would not be lining up just because Chile is "happy to have anyone". They have their own vibrant culture. If it were so easy to fill up venues in South America, every band would be down there as often as possible.
It probably has to do with Morrissey's songs meaning a lot to people, whereas who cares what Marr's singing about? The people buying Marr records just wanna hear if he's got some pretty new guitar riffs. His songs don't say much to people about their lives. Marr is content trying to please aging white hipsters, his small subculture of like-minded musicians, and a music press that rewards conformity and mediocrity. According to Google Trends, interest in him is mostly isolated to the UK, Ireland, Sweden, Australia, and New Zealand.
Pull up YouTubes of Morrissey performing in Chile. Witness the emotional reactions from the audiences. They love his songs and know them well. But of course, as some of Morrissey's songs probably saved their lives.