PHPLIB is the only driver that have named the method MongoDB\Database::selectCollection($name) 

• In mongosh and Java it is named db.getCollection(name) 
• In python it's the same name in snake case:  Database.get_collection().

Proposition: 

• Add MongoDB\Database::getCollection($name)
• Deprecate MongoDB\Database::selectCollection($name)

Benefits: it is easier to translate a query from PHP to mongosh and vice versa.