Recent research on bound states in the continuum (BICs) in photonic waveguides relied mainly on structures that exhibit the effect of lateral leakage. However, the propagating BICs that are supported in such systems have some limitations: they are localized in or in the vicinity of high-refractive-index materials, they are observed as quasiTM polarized waves, and they appear only for certain 'magic' sets of parameters. Here, we demonstrate two simple waveguide systems that enable alternative mechanisms of BIC formation. In contrast to the previously described configurations, the first geometry, consisting of a rectangular waveguide coupled to a planar waveguide, facilitates genuine guiding of quasi-TE modes in the core with the lower refractive index. The second system, proton exchanged waveguide in Z-cut thin-film lithium niobate, can support very low-loss TM-polarized quasiBIC modes for a range of waveguide widths not limited to 'magic widths'