Amazon.com Inc.’s Prime subscription service hit a new high of 180 million US shoppers in March, an increase of 8% from a year earlier, according to Consumer Intelligence Research Partners, which has tracked Amazon memberships since 2014.The increase shows Amazon’s promise of fast delivery on a wide assortment of goods continues to have strong appeal with shoppers grappling with inflation despite greater online competition from Walmart Inc. and China-linked companies such as TikTok Shop, Shein a...