I think the control of Singapore's cars is a reason why they can make a shift away from petrol/diesel cars, not against it. Electric vehicles primarily move pollution from the daily usage in dense urban areas, to remote production and recycling. For Singapore this is ideal as it means cleaner air. The local environment is very much a concern for Singapore.

The market effect on BMW, Mercedes, etc... is probably not much of a concern on them as most car manufacturers are introducing electric models, with BMW having a major share of the electric car market in some places. Tesla currently has a good market share in the prestige range but that is decreasing.

The oil & gas companies are also getting in on the act, so they're reducing the impact on the introduction of electric cars. The first charging station in Singapore is in Shell petrol station. They might prefer hydrogen fuel cell cars as it maintains the need for their distribution network, but they'll adapt either way.

As to maintenance, Tesla's quality issues mean there's no shortage of work. I used to live near a Tesla workshop and it was always overfull with cars needing expensive repairs.